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CMD+scroll wheel no longer dynamically changes the font size on web pages and closed caption/subtitles on videos. How to restore/fix?

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Have a 2019 Mac with latest Firefox software installed. Can no longer use the scroll wheel on the mouse to adjust fonts to variable sizes on web pages and closed-captioning on YouTube. Instead, the entire image (page/video) either enlarges or shrinks. Sometimes there is no adjustment at all when I use the scroll wheel.

This feature still works correctly on my 2011 Mac/Firefox (i.e., CMD+scroll wheel adjusts the font size).

Do you know how to restore the settings on the 2019 Mac so it will once again allow variable font size adjustment on web pages and closed captioning/subtitles?

Have a 2019 Mac with latest Firefox software installed. Can no longer use the scroll wheel on the mouse to adjust fonts to variable sizes on web pages and closed-captioning on YouTube. Instead, the entire image (page/video) either enlarges or shrinks. Sometimes there is no adjustment at all when I use the scroll wheel. This feature still works correctly on my 2011 Mac/Firefox (i.e., CMD+scroll wheel adjusts the font size). Do you know how to restore the settings on the 2019 Mac so it will once again allow variable font size adjustment on web pages and closed captioning/subtitles?

All Replies (1)

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There was a note about that in the Firefox 109 release notes:

On macOS, Ctrl or Cmd + trackpad or mouse wheel now scrolls the page instead of zooming. This avoids accidental zooming and matches the behavior of other web browsers on macOS.

But it sounds like instead of the page scrolling you are getting something more like "pinch" or "magnification" zoom. Could you check this setting:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk.

More info on about:config: Configuration Editor for Firefox. The moderators would like us to remind you that changes made through this back door aren't fully supported and aren't guaranteed to continue working in the future.

(2) In the search box in the page, type or paste mousewheel.with_meta.action and pause while the list is filtered (on Mac, "meta" key refers to the Command key)

(3) Double-click the preference to display an editing field, and change the value to 3 then press Enter/Return or click the blue check mark button to save the change. For reference as to what different values do:

  • 0 => ignore the action
  • 1 => scrolling normally (default on Mac OS)
  • 2 => go back or go forward in tab history
  • 3 => standard/reflowing zoom (previous default on Mac OS)
  • 4 => flip to horizontal scroll
  • 5 => pinch/magnification zoom

Success?