Well linux requires that you do some reading before jumping in, some basic knowledge of computers and the willingness to read directions, follow directions, and be able to figure some things out on your own. Windows does too, just in a different way.
check the ownership/permissions on that file, it needs to be readable and writable by root, it should be, you can find out with ls -l /etc/X11/
whats happened here is quite common with some of the distros like Suse, they dont handle being misconfigured very well, when the routine it uses to figure out what hardware you have fail, or a user goofs and enters the wrong info, it can be somehwat difficult to fix
Yast should let you change this stuff I think, whether or not it stays that way after a reboot I dont know, it should.