I don't really know exactly how to change resolution, on mandrake but I know how to change the font size in Mozilla and make it permanent, I use to have the same problem. If you are using Mozilla-firefox you can click on Tools > Options and under General look for Fonts & Colors then where it says Display Resolution pick 72 dpi and then on Minumum font size, choose some where around 13 or what ever you want, according to how big you want everything to show up. Also you should try to get mozilla-firefox from what I hear it's much better. It's easy to install thrue urpmi, you can click
here to set them up just incase you haven't done so, and all you have to do is su to root and type the following,
CODE
urpmi mozilla-firefox
Hope this helps,
-Luis