How do I get in /etc/X11/xorg.conf to add lines?
If you don’t know how to edit it. Are you sure you know what you are going to add/edit?
kde:
kdesu kwrite /etc/X11/xorg.conf
gnome:
gnomesu gedit /etc/X11/xorg.conf
When open go to save as and call xorg_backup.conf
Then close.
Re open xorg.conf
If you have an NVIDIA card, you can use nvidia-config but for any Xorg.conf changes to “take” you need to run it as root.