Select a song or soundtrack from your Music library, then click OK.
Use Memory looks to apply consistent colour and style adjustments to all the photos in a memory.
In the Photos app on your Mac, click Memories in the sidebar.
Double-click a memory.
To stop playing a memory, press the Space bar.
Click the More button on your Mac, click Memories in the sidebar.
Scroll through the memory, then pause it when the photo you want as the key photo appears.
You must pause the memory to choose a key photo.
Click the More button Change settings in Photos on Mac