Photos slideshow changes order of photos
I have figured out how to keep the order of photos in album when creating a slideshow. I have tried the suggestions made in the community, but they did not work with the latest version of Photos (5.0). Once you have created an album and have the photos in the order you prefer. Select the album you created, then in the menu bar select Edit and Select All. All photos should now be selected. Next select File, Create, Slideshow, and Photos. The name of the slideshow will be the same as the album. Your slideshow will now be in the same order as the album.
iMac 21.5" 4K, macOS 10.15