Theme Font and Size Changer is a Firefox add-on that offers to change the default Firefox font and size with a few mouse clicks.

The Firefox add-on adds an icon to the Firefox statusbar (or add-on bar if Firefox 4 is used). A left-click on the icon opens a simple menu with pulldown menus to change the Firefox font and size of the font.

The font listing is directly taken from the system font directory. Normal, which means default, options are available to make it easier to restore the default font settings of the browser if the need should arise.

The font change affects Firefox menus, toolbars, windows and other native graphical user interface elements. It does not affect the display of fonts on websites.

It is ideal for users who want to increase or decrease the font size and type of the interface because of specific requirements.

Visually impaired users can for instance increase the size of the font easily without changing the font type. This may also be helpful for widescreen users or users with high definition monitors.

The extension is not only compatible with the Firefox web browser, it is also compatible with the Mozilla email client.

The Firefox add-on is compatible with all Firefox versions from 3 to the latest Firefox 4 builds. Thunderbird users can download the extension from here.

I knew that there was a setting somewhere in Firefox that would let me pick fonts. You can access it in the Firefox options (Tools > Options). A click on the Content tab reveals a section entitled Fonts % Colors and a click on the Advanced button in that section leads to a new windows where fonts for specific elements on websites can be selected. The problem that I encountered was the Monospace font. I changed that to the Cambria Font and everything turned back to a readable normal state.

I’m probably not the only one encountering this behavior and I thought it would be great to have it on paper so that everyone can look it up in case they do not know how to edit the fonts in Firefox.