@kericson If you mean just changing the login picture, you just have to rename the picture you want to use as Mojave.heic and replace the one that already exists in /Library/Desktop Pictures

Gabe Shackney
Princeton Public Schools

@gshackney Just tried that; seems to work when you set this and then do a log out. A restart you don't see this image.

I found you have to do this after.

If you have FileVault enabled, change a login option in System Preferences. For example, whether to show a list of users or name and password fields. Just change it back if you don't actually want it changed.

How do I change the login screen background in macOS Mojave?