Only tty7 can detect the monitor and set proper resolution

When I log in with tty7 (the default one) the monitor gets detected and the proper resolution is set. But when I log in with another user without logging off first I get another tty and the monitor isn't detected ad the proper resolution isn't set. How can I get all ttys to detect the monitor? I use Ubuntu 18.04 with Nvidia drivers.

Xorg runs on vt7 ... you an run another Xorg on another tty and have gui on both users.
this might help ...

I already have gui in both users, the problem is that when both users are logged in at the same time the wrong resolution is set for one of the users and the settings say the monitor isn't detected and I can't set the correct resolution.