Photos library in multiple locations on Mac Sequoia

Ok, again, by default, the Photos app's library is located in the \<User>\Pictures folder. At some point, another newer one was created in the \Applications folder. This would have had to happen by choosing another location for the app to save photos to.

Regardless, if you are sure that the one in the \Applications folder is newer, AND it contains all of your photos, I suggest you do the following.

1. Rename the Photos Library.photoslibrary file in the \Pictures folder to something like: Photos Library.photolibrary.old
2. You know have the choice to leave the one in the \Applications folder, or (I would recommend) move it to the \Pictures folder. That latter folder should now have two copies of the Photos Library.
3. Hold down the <option> key, and the, open the Photos app.
4. In the dialog box that opens up, select the "new" library for Photos to use.
5. Close the Photos app, and then, reopen it.

To verify that the correct library is now considered the System Library:

1. Open the Photos app normally.
2. From the Photos' menubar, select Photos > Settings
3. On the General tab, note two things:
   1. Library Locations = <User> > Pictures > Photos Library.photoslibrary, and
   2. "Use as System Photo Library" is greyed out.

You can either retain the .old version of the library in the \Pictures folder; save it to an external drive as an archive copy, or just delete it.

By default, there shouldn't be any references to the Photo Library in the macOS Applications folder, only the icon for the Photos app itself.

If you right-click on this reference, and then, choose "Get Info" it should provide you with the path to where it is pointing to. If this happens to be the same as the one in the /Pictures folder, then this reference is nothing more than an Alias to that location. One way to verify that is that the Alias icon has a small curving arrow on the bottom-left of it ... like in the image below:

Let's start by seeing where the Photos app thinks its Photo Library is located.

1. Run the Photos app.
2. From the app menu, select: Photos > Settings
3. On the General tab, you should see "Library Location," followed by the where the photos library directly path.

By default, it should be located at: <Your user account>/Pictures/

Have you every started the Photos app by first holding down the <option> key? Even if you haven't, try it now. You should see a pop-up dialog box where you can select which Photos Library you want the Photos app to open.