You can set the layout.css.devPixelsPerPx pref on the about:config page to 1.0 (current default value is -1.0) to restore the behavior of previous Firefox versions.

You can make further adjustments and start with a value of 1.0 and adjust this value with 0.1 steps or 0.05 for finer adjustments to make icons on the toolbars look right.

• Use values between 1.0 and about 0.5 to reduce elements in size (do NOT go all the way to 0.05!)
• Use values greater than 1.0 to magnify and make elements larger (percentage divided by DPI, % / DPI).

Use this extension to adjust the font size for the user interface:

• Theme Font & Size Changer: https://addons.mozilla.org/firefox/addon/theme-font-size-changer/

You can look at the Default FullZoom Level or NoScript extension if web pages need to be adjusted after changing the layout.css.devPixelsPerPx pref.

• Default FullZoom Level: https://addons.mozilla.org/firefox/addon/default-fullzoom-level/
• NoSquint: https://addons.mozilla.org/firefox/addon/nosquint/

• https://support.mozilla.org/kb/forum-response-Zoom-feature-on-Firefox-22

Already tried changing the layout.css.devPixelsPerPx pref. Currently set at 1.25.

It did not change the drop down context menu text size - the address bar text size - or the search bar text size. These are the three that are too small to read - unless you are close to the monitor.

The text below the address bar - and webpage text - is a readable size.

Did you try the extension?

• https://addons.mozilla.org/firefox/addon/theme-font-size-changer/

Thank you for your help... The "Theme Font Size Changer" add-on fixed the problem.