Photos
How do you rename a photo/group of photos on the Mac?
MacBook Pro 15″, macOS 10.12
Question marked as
Top-ranking reply
You can't rename the files - but you can add a title which will show instead of the filename in most views.
Select the image and press CMD-i to show the info window, and type in a title. You can use the arrow keys to step to the next/previous and then add another title.