Way 1. To zoom the whole browser. This will change more than the tabs.

   Open about:config

   Search for layout.css.devPixelsPerPx

   Change the value Slightly, such as 1 to 1.1 or more. The larger the value is, the bigger the contents are. Be careful, this may zoom in or out too much to see the viewport.

   Open about:config

   Search for toolkit.legacyUserProfileCustomizations.stylesheets and toggle it to true.

   Go to about:profiles

   Find your profile's Root Directory and click Open Directory.

   In your profile directory, create a folder called chrome

   Open the chrome directory, and create a text file named userChrome.css

   Put the text below into the userChrome.css file

I had to restart firefox but when i did it reset all my settings. I tried to increase the zoom through about:config but it does not work anymore. I've tried both ways below-nothing works/changes. Please help, it is extremely difficult to read my toolbar. This should just be a simple setting, ugggh. Way 1. To zoom the whole browser. This will change more than the tabs. Open about:config Search for layout.css.devPixelsPerPx Change the value Slightly, such as 1 to 1.1 or more. The larger the value is, the bigger the contents are. Be careful, this may zoom in or out too much to see the viewport. Way 2. To change the font size only of specific parts. This would be harder but safer. Open about:config Search for toolkit.legacyUserProfileCustomizations.stylesheets and toggle it to true. Go to about:profiles Find your profile's Root Directory and click Open Directory. In your profile directory, create a folder called chrome Open the chrome directory, and create a text file named userChrome.css Put the text below into the userChrome.css file