I upgraded to Zorin 17 and now the multi monitor option in gone. I have an old NVIDIA graphics card (NVIDIA GeForce GT 750M Mac Edit) and I am running x11 (I don't see an option to use wayland).
These are my driver settings:
I thinks there is something wrong with the drivers, because Blender is also running very slow, and on Zorin 16 is worked fine.
When You are on the Login Screen click on Your Profile/User Name. Then the Password-Field appears. And when it appears in the lower right Corner should be a Gear Icon. Click on it and You should be able to change.
If this should not work look in this Thread. Maybe this will help You.