Reset the page zoom on pages that cause problems: View > Zoom > Reset (Ctrl+0 (zero); Cmd+0 on Mac) See http://kb.mozillazine.org/Zoom_text_of_web_pages

If you have increased the minimum font size then try the default setting 'none' as a high value can cause issues like you described.

• Tools > Options > Content : Fonts & Colors > Advanced > Minimum Font Size (none)
• Tools > Options > Content : Fonts & Colors > Advanced > [X] "Allow pages to choose their own fonts, instead of my selections above"

See also Websites look wrong or appear differently than they should

That worked fine, but now the lettering is very small and hard to read?

Some extensions that you can look at:

• Default FullZoom Level - https://addons.mozilla.org/firefox/addon/6965
• NoSquint - https://addons.mozilla.org/firefox/addon/2592

If you need to increase or decrease the size of fonts and other elements in the user interface and web pages then increase the String pref layout.css.devPixelsPerPx from 1.0 to 2.0 in 0.1 steps to see what works best.
In current Firefox versions this pref is a String value parsed to a float and allows to fine tune the dimensions of all elements (user interface and web pages) more precisely.

• http://kb.mozillazine.org/about%3Aconfig

@Nanman: I am having the same problem.

I am trying to watch YouTube videos and read people comments.

But I can't read peoples comments on YouTube and or other web sites.

Because all or most of the comments/text/images are squished together or almost on the exact same line.

Some of the images do not come up clearly or do not show at all on the web pages.

It also happens on other pages like www.noaa.gov. (A weather web site)

How do you fix this text/font/character problem?