Moving Iphoto Library

New Mini M2 in March. Had a couple of old 2017 iMac photo libraries, one of which was really old and the Photo's app did not import. Tried the second one and it worked.

Been ok for the last few months. One thing have been watching is the analyzing photos/scenes/duplicates message that has been going since April with no end in sight. This is on less that 20k of photos and a couple of dozen short (less than 5 min) videos.

Have read a few things here to see if that process is stuck on something.

In doing so I find the library location for photos is: <home dir> -> Desktop -> Photos library.

I had copied the backups to my desktop and imported from there, but it appears that the proper location is <home dir> -> Pictures from what I read in docs, and indeed what I recall from iPhoto use on the old iMac.

How can I move my Photo library to the proper location? The button in Photo settings called Use as System Photo Library is greyed out so I'm guessing the desktop is now the default location for the photo library.

Thanks.