You can set layout.css.devPixelsPerPx to 1.0 (default is -1) on the about:config page. Adjust its value in 0.1 or 0.05 steps like 1.1 to enlarge or 0.9 to reduce until icons/text looks right. You may need values above 2.0 if you have a high resolution display but make sure not to use values too large or too small.

• modifying layout.css.devPixelsPerPx affects user interface and webpages (global zoom)

Firefox has a Zoom section in Settings to set the default zoom level for webpages.

• Settings -> General -> Language and Appearance -> Zoom

You can open the about:config page via the location/address bar. If you get the warning page, you can click the "Accept the Risk and Continue" button.

• https://support.mozilla.org/en-US/kb/about-config-editor-firefox

WARNING: Changing preferences through about:config not officially supported Hidden settings edited using the about:config tool are explicitly not supported, which means that Mozilla makes no guarantees they will be supported in the future, or that Mozilla will fix them if they break. Mozilla does not test these preferences, and will not in the future. That includes security and performance testing which these preferences may affect.

Ryan, If toolbar text and menu items are too small, the best way to adjust it is through the macOS System Preferences, so it will affect all apps. Go to System Preferences > Display, then set the resolution to Scaled. From there, you can adjust it to whatever you like.

Hi ryan, I will try to explain the steps as simple as possible please try the following steps:

1) Click on new tab , type about:config in the search bar and press Enter. A message will show up on your screen , Click the button accepting the risk. - You should see a page with a search bar named "search preference name".

2) In the "search preference name" search bar , type in the word devp. - A result named " layout.css.devPixelsPerPx" will show up on the drop down lists.

3) click on the pen icon on the right side of the drop down list for layout.css.devPixelsPerPx , then changes its value to 1.5 or 2.0 and press enter. - The bigger the number the bigger the size of your menu fonts ,i personally recommend the size of 1.25 is more than enough.

- Don't enter over 4.0 as it is very hard to read at that point haha.

4) voilà! you are all set !

WARNING: Changing preferences through about:config not officially supported

Hi frogfrog1218, Please remember to warn users that settings edited using the about:config tool are explicitly not supported, thanks.