In web pages, or in the menus and toolbars? --- ''In web pages,'' you can use the zoom feature. More information: [https://support.mozilla.com/en-US/kb/Page%20Zoom Page Zoom | How to | Firefox Help]. If you have the same problem on most sites and find you have to keep zooming them, you can zoom all sites using this add-on: [https://addons.mozilla.org/en-US/firefox/addon/2592/ NoSquint]. After setting your Global zoom level, you can still fine-tune the zoom on individual sites. After installing NoSquint, click the % on the Add-on Bar to call up site preferences, then click the Global Settings button, then the Zooming tab. If you don't have the Add-on Bar displayed, you can right-click the new tab button ("+") or a blank area of the tab bar to the right of it and choose Add-on Bar from the shortcut menu. You can experiment with sizes larger than 125%, but I wouldn't go much higher than 150% unless you have a large high-resolution monitor. If there are particular sites that still present a problem, feel free to post their URLs. --- ''In menus and toolbars,'' try this add-on to change the font size: [https://addons.mozilla.org/en-US/firefox/addon/theme-font-size-changer/ Theme Font & Size Changer :: Add-ons for Firefox]. Does that fix it?