Reset the page zoom on pages that cause problems.

• View > Zoom > Reset (Ctrl+0 (zero); Cmd+0 on Mac)
• http://kb.mozillazine.org/Zoom_text_of_web_pages

You can use an extension to set a default font size and page zoom on web pages.

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

Cor-el... thanks for responding. I know I can zoom in on the pages - in fact, as noted - I can't read anything unless I do that. Thanks for the add-on suggestions - but the fact is... I think the idea of having to install an add-on JUST to be able to read a page is ABSURD. I have no clue why anyone thinks Firefox is a good browser... I have nothing but trouble with it, and apparently I am not alone. I only use it for one site that doesn't support Chrome - which, by the way, NEVER has any issues.

If you increase the minimum font size in Options > Content then you can get problems on pages, especially if elements are positioned absolutely. You can zoom pages instead, but that requires to repeat it with every domain.

The above mentioned extension can manage that more easily and allow to set a minimum, so you can see all web pages more easily without getting the above mentioned problems with overlapping text.
So please take an look at them and try them out to see if it works for you.

I tried NoSquint (looked simpler) and that does the trick... I'm now back to where I was before that upgrade. Thanks.

You're welcome