TimeMachine encryption - does it use password from Disk Utility or the one set when setting up as TimeMachine?

[ThisIs🐵]

Hello,
I have formatted my external HDD as APFS Encrypted with some password, and then I've set up this HDD as TimeMachine with "encrypt" option selected and it asked for another password.
Did this second password "cancel" the previous password, which I have set up when formatting it as APFS Encrypted in Disk Utility?
Can I forget this previous (Disk Utility) password, and only remember the second (Time Machine) password?

 

[NoBoMac]

Second one.

What seems to be happening is that even though you already are encrypted APFS, Time Machine setup is deleting the APFS volume as it's not assigned a role of "Backup". Erases old volume, creates a new one with proper role and assigns the password provided in TM setup. Annoyed me when setting up a new TM drive that was already APFS.

Not versed enough in APFS to understand why that seems to be happening, as command line Disk Utility has a "changeVolumeRole" so seems easy enough to just change the role (have not messed with that). But, it is what it is.

 

[ThisIs🐵]

Thank you!