1. Open Firefox. 
2. In the address bar type in about:config and press Enter.
3. Click I’ll be careful, I promise. 
4. Type mousewheel.with_control.action in the Search bar at the top of the about:config page. 
5. Double-click mousewheel.with_control.action from the Preference Name column. 
6. Enter the number 0 in the dialog box. 
7. browser.gesture.pinch.in (cmd_fullZoomReduce -> empty string)
8. browser.gesture.pinch.out (cmd_fullZoomEnlarge -> empty string)

1. Click OK. 

In order to disable multi-touch pinch zoom-in and zoom-out repeat the procedure as previous one and set:

browser.gesture.pinch.in & browser.gesture.pinch.out to false.
Alternatively you could try setting zoom.maxPercent & zoom.minPercent to 100 …

• disable firefox zoom
• disable mouse wheel zoom in firefox
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