It depends on how your starting X. If your logging in thru a graphical login you should be able to select the session type there thru preferences and such. I don't remember with Suse what it allows to be done, for security they configure it a bit different.
If your starting X from the command line with startx command then your session is customizable with a .xinitrc file. For user preferences/configurations you have all these hidden files in your home directory, this is were your preferences are kept because as a user you don't have much rights outside your home directory. The dot before the filename makes them "hidden".
I am not a kde user, but I think the command you use would be "startkde". So if your using startx then go:
echo "startkde" > ~/.xinitrc
and that should be enough.
If your logging in thru the GUI look for a preferences or session thing you can select. You should be able to pick what you want to use fairly easily.
To fix your small fonts problem in Gnome you use a tool called "gnome-font-properties". If you go thru the applications menu ---> desktop preferences ---> Font, and then fix your fonts.
OR
If everything is too small to read, then open up a terminal. The icon looks like a gray tv screen with a small >_ text in it. It may be on the bar itself, click on that, if isn't then go into applications --> System Tools ---> Terminal
once you get the xterm open type:
gnome-font-properties
and hit enter, that will open the font preferences and you can select bigger fonts that way.
Hope that helps.