I have an early 2015 MacBook Air. Forgot the name of the OS it originally came with, but now using Catalina. When I first got it, I set the screen saver to randomly shuffle through Photos, and I have kept to that. However, I am noticing several photographs coming up which I can no longer find in Photos; I believe I deleted them from Photos quite some time ago. I just now went to Settings>Preferences>Screen Saver and found that the source was labelled "pictures". Not sure I know what "pictures" is suppose to be as a source; thought it was Photos. Went back through my Photos and I cannot find that particular images that keeps popping up randomly. Could someone please tell me what "pictures" means as a source for the screen saver, and then how I can go back to edit what is in pictures? Thanks!!