Change the fonts in Firefox 3
Step 1: Open the "Fonts" window
Click on "Tools" in the menu bar and select "Options" from the drop-down menu, or press Alt+T and then press O.
Click on the "Content" tab (as shown in fig. 1), or use the left and right arrow keys to cycle through the tabs until it is selected.
Under the "Fonts & Colors'" header, click the "Advanced" button or press Alt+A. This will open the "Fonts" window, shown in fig. 2.
Step 2: Choose the fonts for all web pages you visit
In the "Fonts" window shown in fig. 2, click on the drop-down list next to "Proportional" or press Alt+P. Use the mouse or the up and down arrow keys to select whether you want proportional text to be serif (such as Times New Roman) or sans-serif (such as Arial).
Select a specific serif font by clicking on the drop-down list next to "Serif" or by pressing Alt+S. To select a sans-serif font, click on the drop-down list next to "Sans Serif" or press Alt+N. For either, use the mouse to scroll through the available fonts and click on the one you want, or use the up and down arrow keys to scroll through the available fonts until the one you want is highlighted.
You can also change the font size here by using the drop-down menus on the right.
To tell Firefox to use your font choices, untick the box beside "Allow pages to choose their own fonts, instead of my selections above" by clicking on it or by pressing Alt+A.
Click on the "OK" button, or press Tab until it is highlighted and press Enter, to return to the "Options" window (fig. 1).
Click on the "OK" button, or press Tab until it is highlighted and press Enter, to finish and return to Firefox.
Note: If this does not work it could be because your computer settings cannot be changed due to local IT policies--contact your local IT support for further help.