Yes right click on a toolbar, the customize option allows ordinary or small icons. Other options are to look at Operating System settings, or to adjust some of the Firefox preferences, and I also note mention of an add-on https://addons.mozilla.org/en-US/firefox/addon/theme-font-size-changer Additionally there are add-ons that change content size. See also [https://support.mozilla.com/en-US/questions/772884#answer-126017 thread] '' " I would like to make the font sizes on my menu bars, tool bars, and tabs larger. How can I change those font sizes only? " '' If anyone does change the ''layout.css.devPixelsPerPx'' in Firefox 4 I would be interested in what happens, there is a possible bug as mentioned in [https://support.mozilla.com/en-US/questions/791213 4.0RC1 - Bookmark hover fault]