How to Fix Firefox Not Scrolling with UpDown Arrow Keys or HomeEnd Keys
If you’ve encountered a problem where your Firefox installation no longer scrolls when you use the up or down arrow keys, and even the Home or End keys don’t work anymore, there’s an easy fix.
When this problem happens, you’ll notice that moving the arrow keys around just moves the cursor around the page.
The problem is because you tripped the Caret Browsing feature at some point, and accidentally hit Yes.
“Caret Browsing” is a feature of Firefox which allows you to navigate a page just like a document in MS Word or any other word processing application. You can move the cursor between lines using arrow keys and can select the text or click on any link using your keyboard.
To fix this, you can just hit the F7 key again and choose No to turn off Caret Browsing. Or, if you want to do it the about:config way, filter by accessibility.browsewithcaret and make sure it’s set to false.
Remember, you can double-click on any boolean value to toggle between true and false.