You can look at this extension to adjust the font size in the user interface.

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

You can set a global zoom via the Options/Preferences of the extension (about:addons or the Tools menu) that modifies layout.css.devPixelsPerPx. Modifying layout.css.devPixelsPerPx affects user interface and web pages (global zoom).

You can look at the NoSquint Plus extension to set font size (text/page zoom) and text color on web pages.

• https://addons.mozilla.org/firefox/addon/nosquint-plus/

Thank you for the answer. I'll play with that tomorrow, but I ask why did this change have to happen with the update? Everything was fine as it was before. As a consumer, i should not have to make adjustments because of an update. I am no whiz, just a simple emailer and information gatherer. 1st time a Firefox update has caused me worry. again, thank u for your offer of help.

iamlightnow said

I ask why did this change have to happen with the update? Everything was fine as it was before.

I don't think there was an intentional font size change between Firefox 53 and Firefox 54. There have been some text and graphics rendering changes in recent versions, so if you skipped a few versions, that might be the issue. Otherwise, possibly a while back you did something to increase the font size -- add-on, custom style rule, setting -- and that workaround got broken by the update, or lost in a "Refresh".

Well, I have not missed a single update and the only add-on I have is a Yahoo email ad blocker. I do not know what a "custom style rule" is, so I'm sure I did not do that, at least, not on purpose. I would just like my screen to go back to how it was before the 54.0 update.

Can you tell me what a custom style rule is please. thanks for your input.

A custom style rule is a bit of code that modifies the appearance of Firefox's user interface. It can be installed a file named userChrome.css that you would have had to create yourself, or through an extension such as Stylish (user style) or Greasemonkey (user script). If that doesn't sound familiar, it must be something else.

The key setting affecting the size of fonts in the user interface and content area, as cor-el mentioned, is layout.css.devPixelsPerPx. The usual way to modify that is through the about:config preferences editor. Do you remember ever doing that?

The standard setting for that preference is -1 which simply uses the system level scaling factor (called Text Size on Windows) to adjust the display. Your Text Size on Windows 8 might be 125% by default. Firefox then would adjust all the text sizes by zooming them up 25%.

Setting layout.css.devPixelsPerPx to 1.0 forces Firefox to use 96dpi like older browsers. That will look rather small on a high resolution display. You can manually adjust the setting to a higher zoom (e.g., 1.5 is equivalent to 150% zoom). But be careful not to see the value to between 0 and 1.0, because the text may become unreadably small, which is a hassle to recover from.

This could be related with the recent switch in Firefox 52+ from Cairo to Skia for canvas/content rendering.

Firefox 52+ has changed from Cairo to Skia for canvas/content rendering.

• https://www.mozilla.org/en-US/firefox/52.0/releasenotes/
• When not using Direct2D on Windows, Skia is used for content rendering

You can modify these gfx.*.azure.backends prefs on the about:config page to revert to the old font rendering swap the skia,cairo order to cairo,skia or remove the skia and leave cairo.

• gfx.canvas.azure.backends = direct2d1.1,cairo,skia
• gfx.content.azure.backends = direct2d1.1,cairo,skia

You can open the about:config page via the location/address bar.

You can accept the warning and click "I'll be careful" to continue.

• http://kb.mozillazine.org/about:config

I appreciate both these replies, but too far out of my simple user computer realm. For now, I will just get used to the smaller font, and maybe things will change with future updates.

To cor-el: I did add-on the Theme Font & Size Changer, and I got back my Bold Titles, which is what I really missed. But now my menus are bold too and i can't change them, even with Windows Display options, but no problem. Simple fix for me. All I needed. I can keep playing around with this add-on safely! thanks!

I don't want to hijack another's post, but I have a similar question & can't see where to post a new question in the Support Forum. Perhaps someone here can help me to find an answer? My question is: How do I adjust the Firefox Menu Bars? My FF display has an entire bar at the top devoted to repeating the page topic, and it duplicates the text in the page tab 2 lines below. How can I delete the top line of redundant information?

Hi JJJoseph, the line at the very top is called the "Title Bar" and there is a checkbox to turn it on/off in the Customize pane (lower left):

Customize Firefox controls, buttons and toolbars