So you’ve recently installed or upgraded Kubuntu to 9.10 Karmic Koala and installed Firefox. To your horror, you find that all the menus and labels in the browser’s interface are either HUGE or tiny relative to the included KDE applications. Here’s the quick fix.

1. Click on the K menu
2. Select System Settings
3. In the Look & Feel section, click the Appearance icon
4. In the left panel, click the Fonts icon
5. At the bottom of the Fonts settings, the Force fonts DPI drop down list control is set to Disabled by default
6. If you want to make Firefox’s fonts smaller, select 96 DPI; to make them larger, select 120 DPI
7. Click the Apply button
8. Restart Firefox

If you’re using Ubuntu with the Gnome desktop and run into this problem, there should be a similar DPI setting for either fonts or the display. Let me know how you resolved it on Gnome.