Your minimum font size is very large. Firefox uses that as an override and does not expand the layout to make it fit. For better results, lower your minimum font size to, say, 10, and use zoom to enlarge text.

If you find it tedious to zoom every site, there's an add-on for that. See: Default FullZoom Level or for more features NoSquint.

If you have made changes to Advanced font settings like increasing the minimum/default font size then try the default minimum setting "none" and the default font size 16 in case the current setting is causing problems.

• Edit > Preferences > Content : Fonts & Colors > Advanced > Minimum Font Size (none)

Make sure that you allow pages to choose their own fonts.

• Edit > Preferences > Content : Fonts & Colors > Advanced: [X] "Allow pages to choose their own fonts, instead of my selections above"

You may have zoomed the page(s) by accident. Reset the page zoom on pages that cause problems.

• View > Zoom > Reset (Ctrl/Command+0 (zero))

• http://kb.mozillazine.org/Zoom_text_of_web_pages

Thank you all, fading eyesight made some sites hard to read and turning up the volume seemed to be the cure but I can now manage much better :-)

Kind regards to all

Went with No Squint Jscher :-)