If you find the menu font size in Mozilla Firefox and you think it is hard to read then you can make it larger. This can be done easily using the Firefox add-on Theme Font Size Changer. Here is how :
- Visit https://addons.mozilla.org/ in your Firefox browser.
- Click on the Add to Firefox button to install the Theme Font Size Changer add-on
- Restart Firefox to complete the installation of the add on.
Once you have Theme Font Size Changer installed, you are ready to use it. You can choose the font size from Tools → Theme Font Size Changer and choosing a font size as shown :
If you want to revert back to normal font size, then just choose the font size Normal and Firefox will have original font sizes.