I've got 2 Lenovo P27-U20s daisy chained via TB and they frustratingly swap places all the time.
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External Displays Swapping - Arrangement Not Remembered!
- Thread starter Brenzo
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I've got 2 Lenovo P27-U20s daisy chained via TB and they frustratingly swap places all the time.
So it's been 11 days since I switched my cabling back to HDMI only connections (which caused the swapping problem in March 2022 with my Mac Studio - and dating back to 2010 with my Mac Pro). Since then there has been no swapping problem at all.
BUT, today my 3 monitors were swapped (for the first time in 11 days) when I turned on my Mac Studio . And each time I restarted (several tries) or rebooted (from power down) they stayed in the same swapped state. The only way I got them back to "normal" was to use the Display settings pane to rearrange them back to normal. And then they stayed that way again through 3-4 more trial restarts.
What this strongly suggests to me is that Apple has indeed made a significant change to try to fix this problem. I had never gone 11 days without a swap before using all HDMI connections (2 are TB to HDMI adapters - but I think that is irrelevant to the issue). But even more indicative that some fix was attempted is that after they finally swapped they continued to stay in the same swapped condition. In the past, after a swap (which was random and occurred often) they continued to swap randomly after restarts or reboots.
So I guess (?) what happened is that whatever Apple changed was not perfect, but vastly reduced the occurrences of swaps in my case, but once a swap happened again that setup information became saved so the displays continued to be in the new swapped state (presumably until once again some now infrequent situation would have to occur and cause another swap (which of course I never waited long enough to experience again.)
Bottom line - some fix must have been attempted, and for me worked for 11 days, but isn't perfect so other people's results may vary from mine - swapping more or less frequently.
BUT, today my 3 monitors were swapped (for the first time in 11 days) when I turned on my Mac Studio . And each time I restarted (several tries) or rebooted (from power down) they stayed in the same swapped state. The only way I got them back to "normal" was to use the Display settings pane to rearrange them back to normal. And then they stayed that way again through 3-4 more trial restarts.
What this strongly suggests to me is that Apple has indeed made a significant change to try to fix this problem. I had never gone 11 days without a swap before using all HDMI connections (2 are TB to HDMI adapters - but I think that is irrelevant to the issue). But even more indicative that some fix was attempted is that after they finally swapped they continued to stay in the same swapped condition. In the past, after a swap (which was random and occurred often) they continued to swap randomly after restarts or reboots.
So I guess (?) what happened is that whatever Apple changed was not perfect, but vastly reduced the occurrences of swaps in my case, but once a swap happened again that setup information became saved so the displays continued to be in the new swapped state (presumably until once again some now infrequent situation would have to occur and cause another swap (which of course I never waited long enough to experience again.)
Bottom line - some fix must have been attempted, and for me worked for 11 days, but isn't perfect so other people's results may vary from mine - swapping more or less frequently.
Hi everyone and thank you for the detailed posts and attempts to help. I also made an account just so I can follow and post on this thread. I can attest that identical monitors are NOT the reason for this issue.
I have a Dell (monitor 1), a BenQ (monitor 2 and main) and I'm using the laptop itself as monitor 3 (from left to right). I'm running the latest version of Monterey on an M1 Max with a Satechi Thunderbolt dock. Everything worked perfectly at the beginning of this setup last year. The problem started 4 months ago or so and the only change in my setup has been security updates.
I've read many but not all of the 15 pages so far and I plan on trying the two or three possible solutions I haven't already. Like everyone else this is driving me crazy especially since my whole setup is for work. The many windows I have open on each monitor are for work efficiency purposes and I need them to stay put at startup and on wake. They don't. What I've noticed is that the monitors are now waking from sleep in a different order each time which wasn't happening before and suspect this has something to do with the constant rearranging. But again, different brands therefore different EDIDs.
I was thinking maybe one of the cables is defective but now I'm not so sure. I'll post if any of the solutions work for me.
I have a Dell (monitor 1), a BenQ (monitor 2 and main) and I'm using the laptop itself as monitor 3 (from left to right). I'm running the latest version of Monterey on an M1 Max with a Satechi Thunderbolt dock. Everything worked perfectly at the beginning of this setup last year. The problem started 4 months ago or so and the only change in my setup has been security updates.
I've read many but not all of the 15 pages so far and I plan on trying the two or three possible solutions I haven't already. Like everyone else this is driving me crazy especially since my whole setup is for work. The many windows I have open on each monitor are for work efficiency purposes and I need them to stay put at startup and on wake. They don't. What I've noticed is that the monitors are now waking from sleep in a different order each time which wasn't happening before and suspect this has something to do with the constant rearranging. But again, different brands therefore different EDIDs.
I was thinking maybe one of the cables is defective but now I'm not so sure. I'll post if any of the solutions work for me.
Swapping can also happen between different monitors, if at least one of them doesn't provide the EDID in time for macOS to recover the stored arrangement.
The arrangements are stored in the files at
Now if one of the monitors does not provide the EDID fast enough, the system will not have the correct list of UUIDs to find the last arrangement, so it might create a new one.
This happens sometimes with some docks/hubs/adapters. I get support emails almost every day on Lunar with problems caused by slow-to-connect docks, so it is something to think about. Maybe troubleshoot by connecting without the dock, through a direct DP-to-USB-C cable if possible (to avoid the HDMI-converter chip inside the HDMI-to-USB-C cables)
The arrangements are stored in the files at
~/Library/Preferences/ByHost/com.apple.windowserver.displays.*.plist, and they are retrieved by macOS when monitors connect/disconnect. The system uses the list of EDID UUIDs of the currently connected screens to find the last stored arrangement.Now if one of the monitors does not provide the EDID fast enough, the system will not have the correct list of UUIDs to find the last arrangement, so it might create a new one.
This happens sometimes with some docks/hubs/adapters. I get support emails almost every day on Lunar with problems caused by slow-to-connect docks, so it is something to think about. Maybe troubleshoot by connecting without the dock, through a direct DP-to-USB-C cable if possible (to avoid the HDMI-converter chip inside the HDMI-to-USB-C cables)
Hello everyone,
I wanted to share my experience with you about how I got my 16-inch m1 pro mac to stop swapping the display arrangement and for it remember the arrangement.
Firstly, like many others I went down the rabbit hole of adjusting mission control settings and finding software to fix but there was just none. I even went as far to edit the EDID but that's a separate rabbit hole itself.
To give more context I have two Viewsonic VX2705-2K monitors (sadly they are discontinued). My current setup as of now is one HDMI cable and one thunderbolt cable to HDMI plugged into my mac running at 144hz each.
Running this setup on Monterey 12.6.6 gave me so many issues, not only would the display arrangement swap it would also turn off and on one of the monitors randomly for no apparent reason.
After reading this forum 2 weeks ago I learnt the following, running two identical monitors outputs the same EDID UUID, which causes issues for the mac running on Monterey as it pretty much cannot differentiate between which monitor is which. Editing this might be possible like I read and saw but it might cause more harm than good if you don't know what you are doing.
So, you ask, how did I actually fix this issue for myself. The solution really surprised me, last night I called Apple Support after the arrangements played up again hoping they had some answers for this, and surprisingly they did. They said Ventura 13.5.1 contained the fix specifically for this issue. They said their engineers fixed the issue where on wake from sleep or restart the laptop would forget the screen arrangements.
So, after backing up and upgrading to Ventura 13.5.1 I can confirm it has been fixed for me, normally while typing this my screen would flicker and that has not happened once. On top of that I had taken the laptop with me to bed, away from my setup, and today morning when I plugged it in and turned on with my mouse it remembered exactly which monitor is which. Keep in mind this has never happened before upgrading.
Side note, I made sure to change my settings back to default after upgrading for mission control before doing anything else to essentially have everything running "stock". I have attached a screenshot as reference for anyone who needs it.
I hope my experience helps people on this thread, and if you have any questions on my experience, I will try my best to answer! And if this does work for you, please like this post so others can see
I wanted to share my experience with you about how I got my 16-inch m1 pro mac to stop swapping the display arrangement and for it remember the arrangement.
Firstly, like many others I went down the rabbit hole of adjusting mission control settings and finding software to fix but there was just none. I even went as far to edit the EDID but that's a separate rabbit hole itself.
To give more context I have two Viewsonic VX2705-2K monitors (sadly they are discontinued). My current setup as of now is one HDMI cable and one thunderbolt cable to HDMI plugged into my mac running at 144hz each.
Running this setup on Monterey 12.6.6 gave me so many issues, not only would the display arrangement swap it would also turn off and on one of the monitors randomly for no apparent reason.
After reading this forum 2 weeks ago I learnt the following, running two identical monitors outputs the same EDID UUID, which causes issues for the mac running on Monterey as it pretty much cannot differentiate between which monitor is which. Editing this might be possible like I read and saw but it might cause more harm than good if you don't know what you are doing.
So, you ask, how did I actually fix this issue for myself. The solution really surprised me, last night I called Apple Support after the arrangements played up again hoping they had some answers for this, and surprisingly they did. They said Ventura 13.5.1 contained the fix specifically for this issue. They said their engineers fixed the issue where on wake from sleep or restart the laptop would forget the screen arrangements.
So, after backing up and upgrading to Ventura 13.5.1 I can confirm it has been fixed for me, normally while typing this my screen would flicker and that has not happened once. On top of that I had taken the laptop with me to bed, away from my setup, and today morning when I plugged it in and turned on with my mouse it remembered exactly which monitor is which. Keep in mind this has never happened before upgrading.
Side note, I made sure to change my settings back to default after upgrading for mission control before doing anything else to essentially have everything running "stock". I have attached a screenshot as reference for anyone who needs it.
I hope my experience helps people on this thread, and if you have any questions on my experience, I will try my best to answer! And if this does work for you, please like this post so others can see
Could a script be put together (which would need to presumably stay running, not just at boot/startup) using a combination of watching the .-list file for changes and ioreg to effectively ensure the ordering is maintained ‘as expected’?
I shifted a few years ago to a single ultrawide + MBP display, and occasionally iPad sidecar, but read the whole thread, have been considering possibly going to a pair of 5Ks, but yeah - 10+ years of this is ‘enough.’ It sounds like ‘fixed mostly’ is the latest?
Probably not the same issue (differing displays) although am sure it’s somewhere in macOS display core code, I’ve seen the ‘main’ display cycle semi-randomly at times, never with any display ‘outage.’ I can’t say definitively if I’ve seen it since switching to an AS MBP, but I’m sure it’ll rear its head again.
Sure, you could script displayplacer for this. It might need a PR for adding support for AlphanumericSerialNumber.
The display cycling (I assume you mean, turning off then on suddenly?) could be caused by electromagnetic interference: https://mastodon.social/@haeckerfelix/110272427676278609
Sorry, was typing on iPad late at night on that one. By cycling, I mean it 'loses' which display has the dock as primary display. No detectable power flicker, screen still on, OS just 'swaps which has the dock'/main display randomly.
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Well, it was gone for me for a while, and I thought Apple had finally gotten off their butts and fixed it, but for the last couple of weeks, it's been the same crap as always. I'm not even mad anymore, luckily I had bought Lunar, which comes with an Apple Shortcut (meaning an instruction set that is a document in the Shortcuts app), so I pin it to the menu bar, and when it swaps monitors I click on the shortcuts icon, choose Swap Monitors, and back to normal.
Apple didn't bother, Samsung didn't bother either. It's the way it is.
Apple didn't bother, Samsung didn't bother either. It's the way it is.
Try this, it works for me
Before waking up the Mac, wake up all the displays manually by pressing the button on each display.
Now wake up on the Mac and everything should be in place where you left.
Ps: I have a Mac mini with 3 display setup -Samsung 49", HP 27", and Samsung 4K 32"
Before waking up the Mac, wake up all the displays manually by pressing the button on each display.
Now wake up on the Mac and everything should be in place where you left.
Ps: I have a Mac mini with 3 display setup -Samsung 49", HP 27", and Samsung 4K 32"
After speaking with a very knowledgeable software engineer that knows a lot about this, I'm almost certain that the ones to blame are Samsung and other display manufacturers that are so lazy that they don't set the EDID serial per unit, but rather per batch or model.
Therefore, macOS gets confused and randomly assigns the display numbers to them, and with that which one is the main and which one is secondary.
When I bought these mediocre Samsungs, my first plan was to buy LG monitors, but someone at LG had the dumb idea to make their backs white. And the thought of having two very white monitor backs in my room didn't appeal too much to me. But LG apparently doesn't do this stupid thing with their displays, so I wish I had bought LGs instead and remove the back covers and paint them black.
But those of you having this problem, the best you can do is pester your display manufacturer to release a firmware update to fix this. In my case I tried, but my two Samsungs are not even regular Samsung brand, but their Display Solutions branch, and all my attempts have been ignored.
Therefore, macOS gets confused and randomly assigns the display numbers to them, and with that which one is the main and which one is secondary.
When I bought these mediocre Samsungs, my first plan was to buy LG monitors, but someone at LG had the dumb idea to make their backs white. And the thought of having two very white monitor backs in my room didn't appeal too much to me. But LG apparently doesn't do this stupid thing with their displays, so I wish I had bought LGs instead and remove the back covers and paint them black.
But those of you having this problem, the best you can do is pester your display manufacturer to release a firmware update to fix this. In my case I tried, but my two Samsungs are not even regular Samsung brand, but their Display Solutions branch, and all my attempts have been ignored.
Are all Samsung monitors "bad" and all LG ones "good"? What about other manufacturers? How can we find out and where can we make a list?
That would be a good idea, however, I can't say for sure that all Samsung monitors have this problem. I know that I have read many posts from Samsung users having this problem, and I have it as well. However, I also had this problem when I had two Dell monitors.
But it would be a good idea to make that list, clarifying that not every unit from the brands in the "Bad" column is known to have this problem, and probably the same can be said for the "Good" column.
It's highly dependent on the monitors in question and whether they have unique serial numbers in the EDID info sent to the computer.
In my case, the Samsungs I have previously referenced in this thread exhibit the issue still. The only reason I haven't replaced them out of annoyance is because I have a quick script I can invoke via key press that instantly swaps them. Since only have two, I know, if they're "wrong", they simply need to swap places.
I've mostly resolved my issue by entirely preventing my Mac Studio from sleeping on its own. It basically stays on 100% 24/7, so when I flip my displays over to the PC, the Mac will remain in whatever state I left it once I switch back. Obviously not ideal as it basically never gets a rest unless I tell it to sleep (and even then, the act of picking up my mouse to switch it back to the PC usually immediately wakes it again) or shut it down completely. 😑
I‘ve been out of the loop for a while, quietly grinding my teeth at the still-persistent swapping of monitors, and just read through the thread again to see if anything had been fixed yet.
This ‘race to connect’ theory makes a lot of sense to me. I find that when I do a soft restart, it’s anyone’s guess how the displays will come back. But if I shut the whole system off completely, wait a bit, then turn it on fresh, it comes back properly. I’ve got a Mac Studio with a Studio Display (“always on”, apparently?) as my primary display, a side Ben-Q, and another side LG.
With a soft restart, the three displays are already powered on, and it’s a mystery how or why the system decides which order to connect the three displays. But with a hard restart, the Studio Display seems to always get there first - which I suppose makes sense.
(By the way, I still leave the computer on all the time, and have my power settings set to never turn off the displays - otherwise they’d be swapping around all day long. Now I only see the issue when I need to restart.)
My displays do not have unique serial number so whatever Mac I tried the past two years, I got this issue all the time.
I don't have a Mac with me. Can you guys/ladies please try if this method could avoid settings getting messed up?
Set the Mac to never sleep.
1. Turn on monitor1
2. Turn on the Mac
3. After login, turn on monitor2
Orders of shutting down probably does not matter.
I don't have a Mac with me. Can you guys/ladies please try if this method could avoid settings getting messed up?
Set the Mac to never sleep.
1. Turn on monitor1
2. Turn on the Mac
3. After login, turn on monitor2
Orders of shutting down probably does not matter.
I hate to revive an old thread that seems to have quieted down. Is no one experiencing this issue anymore? I recently got a CalDigit TS4, which I'm having display swapping issues with; and their Element Hub, which seems to be working perfectly fine. I'm not entirely sure if my particular issue is with macOS or the dock itself.
I have a 16" MBP M3 Pro (running Sonoma 14.5) and two identical HP displays. The displays are connected by USB-C to DisplayPort cables from the dock. As you may have guessed, the EDID UUIDs are the same. The AlphanumericSerialNumber and PortID values are different between the two displays though.
Let's say my displays are A, B, & C. C is the MBP/main display. I don't use clamshell mode.
First, my experience with the TS4:
Back to the TS4... Is this still some sort of macOS issue, or could it be a bug/quirk with the TS4 itself? The issue does go away if I change one of the displays to use an HDMI cable, but I would rather use DisplayPort. It feels more like a workaround than an actual fix, especially when it works fine on the Element Hub.
Curious if anyone else with a TS4 and/or Element Hub has the same experience as me. Both of these docks are on their latest firmware versions.
I was hoping to keep the TS4 and return the Element Hub, but the Element Hub seems to be giving a better experience, so not quite so sure what to do now. I also plan on upgrading my monitors soon. Is the display swapping issue still present with newer monitors? I was thinking of going with a couple from Dell, but haven't decided which model yet.
I have a 16" MBP M3 Pro (running Sonoma 14.5) and two identical HP displays. The displays are connected by USB-C to DisplayPort cables from the dock. As you may have guessed, the EDID UUIDs are the same. The AlphanumericSerialNumber and PortID values are different between the two displays though.
Let's say my displays are A, B, & C. C is the MBP/main display. I don't use clamshell mode.
First, my experience with the TS4:
- When I undock and re-dock, the displays will come back in the correct order, 100% of the time.
- They also have been coming back in the correct order after waking from sleep.
- Only when I power on after a shut down or restart, A and B will have swapped. The mouse cursor does not move between them in the right order, as if someone physically swapped the external displays around.
- To fix this, I can simply undock and re-dock and they'll come back in the correct order, 100% of the time.
- Alternatively, I can rearrange the displays in System Settings...but then A and B are swapped the next time I undock/re-dock and have to rearrange them back again. Because of this, it's easier to just do the first method to get them back in the correct order rather than having to rearrange them.
Back to the TS4... Is this still some sort of macOS issue, or could it be a bug/quirk with the TS4 itself? The issue does go away if I change one of the displays to use an HDMI cable, but I would rather use DisplayPort. It feels more like a workaround than an actual fix, especially when it works fine on the Element Hub.
Curious if anyone else with a TS4 and/or Element Hub has the same experience as me. Both of these docks are on their latest firmware versions.
I was hoping to keep the TS4 and return the Element Hub, but the Element Hub seems to be giving a better experience, so not quite so sure what to do now. I also plan on upgrading my monitors soon. Is the display swapping issue still present with newer monitors? I was thinking of going with a couple from Dell, but haven't decided which model yet.