Thanks for your help. I never did download it, I bought it on DVD years ago. Seems like an 8 track nowadays.
Aha, ok. No further comment.
I was just able to use another iTunes account and the new version of iPhoto is available under purchases, but download isn't an option, just "update" and so far it's not done anything. I click on the update button and it greys out then nothing happens. If I go to another spot in the App store app, and go back to purchases it's not greyed out and pressing the update button again doesn't do anything but grey out the button.
[/COLOR]I'm afraid to uninstall it, for fear of not being able to reinstall it or have my library get funky if I uninstall it.
I tried moving it out of the applications folder to the desktop but the button didn't change to install (I did sign out and then back in).
AFAIK you can't install apps from different app store accounts in the same applications folder/OS X/Mac.
Install OS X on a new volume, sign in new installed OS X 10.10.3 with this other app store account, unmount the common volume, start the app store, and then install iPhoto (on the new volume). After this, mount the old volume, and copy the iPhoto app the your old partition. If that doesn't help copy your iPhoto library to the new volume.