Manually Adjusting Scroll Lines In Firefox

If you’re like me, you use the scroll wheel on your mouse. A lot. With web browsers there is much scrolling and that’s just the nature of how web pages work.

Firefox does have the ability to manually control how many lines are scrolled up or down, and this can be done completely outside Windows Control Panel or KDE/GNOME’s Control Center.

But before I tell you that, if you want ultra-precise scrolling in Firefox, all it requires is a keystroke while doing it. Press and hold ALT, then scroll a web page in Firefox with your mouse. You’ll notice it will scroll “slowly”, one line at a time. When you let go of ALT, normal scrolling resumes.

Note: The above method is a hit-or-miss with a laptop’s touchpad. On some laptops it doesn’t work due to the proprietary nature of how they work. But on regular mice it always works.

Adjusting how many lines Firefox will scroll without the use of ALT (as in normal scrolling) requires only modifying two internal settings.

1. Open Firefox, type the address about:config in the address bar, then press Enter.
2. If you get a warning for “This may void your warranty!” (a joke by the Mozilla team), continue through it.
3. In the Filter search bar at the top – which will appear when you load about:config, search for:
   
   mousewheel.withnokey.sysnumlines
   
   You must type that exactly as shown for it to show up.
4. Double-click this entry. The value will change from True to False.
5. Go back to the Filter search field again. Search for:
   
   mousewheel.withnokey.numlines
   
   You must type that exactly as shown for it to show up.
6. Double-click this entry to edit it. The default value is 1. A “standard” scrolling speed is 5. If you want it “faster”, choose a higher number like 7 or 10. If you want scrolling to be “slower”, choose a number between 2 through 5.

It’s suggested you have another tab opened up to test scrolling. Once modified it immediately goes into effect without having to restart the browser.

On a laptop: You’ve most likely noticed that the web browser scrolls much too “fast”. A setting between 2 and 5 should make scrolling much easier.

On a desktop: It’s probably true you want to make the scrolling “faster”, like Internet Explorer. If you want it to act exactly like IE, change the value to 7. If you want “faster” than that, try 8, 9 or 10. You can go beyond 10 if you wish, but bear in mind if you set it too high, your scroll will act too much like PageDown (which is too much for simple scrolling).