Q: New Photos app and iMovie

I'm sorry but what steps do I take to get to General... Library Location...

Thank you but I think that when I transitioned from iPhoto to Photo I only brought one library over and that is why I'm only seeing only 3 albums with about 300 photos in iMovie, but in Photos under Albums it shows all my photos (52,000+)

There are two libraries, the Photo Library which has 3 albums (which is the library I brought into Photos). Total pics apx. 800  (one album doesn't show # of pics). The iPhoto library directly below shows 21,482 in one album and 42, 24, 12, 185 in four others.  But Photos has 52,577 pictures and is not showing photos from other albums.  Sorry if I'm making this confusing.

This is what is in Photos and iMovie

I don't want to take up all your time, but this is what I see.  in Photos I have the library that I uploaded originally to Photos from iPhoto and I see the most recent pictures from the past 12 months or so.  Now if I click on iPhoto Library in iMovie that is where the "other" library is that didn't get transferred to Photos when I did it originally.  So does it matter that I'm using either library when making a movie?

Thank you for all your help!