Your problem as nothing to do with screen resolution. Two issues 1) your screen DPI setting, and 2) how your application selects the font size for display.
1) With the OS/Kubuntu stuff, ie the system UI things, the font size is pretty much static across the interface. However it will calculate this base on the assumed Dots Per Inch setting for your screen. It is very common for a screen to supply incorrect screen dimensions, etc causing this calculation to be way out. So if your system fonts are too small, you can change the DPI settings in your xorg.conf file... look for an article on the wiki to do with "tiny fonts on kde desktop"
2) Once the desktop is fine.... then fonts within applications (such as web pages) will tend to be driven by what the web site defines... this may not be appropriate for distant viewing, however there is a very simple way to override these settings to make web pages perfectly readable.... in Firefox you just hit CTRL+ and CTRL- to increase and decrease the font size.