Just in case somebody is looking for this. I did find a thread explaining how to set/change the user-photo on the login screen (KDE of course) but it related to a previous version, and all the paths/screenshots in that threads don't apply. So for Xenial:
System Settings / Account Details / User manager
This is where you'll find the large square button next to the user name, which allows you to load an image from file. PNG is recommended. You'll be prompted for your admin. password when you hit "Apply."
Cheers.
System Settings / Account Details / User manager
This is where you'll find the large square button next to the user name, which allows you to load an image from file. PNG is recommended. You'll be prompted for your admin. password when you hit "Apply."
Cheers.