How can I disable the Backspace button's "Go Back" functionality in Firefox?

• Navigate to about:config in the address bar
• set the filter to browser.backspace_action

It is an integer value, change it to the desired setting:

0 - Pressing Backspace will go back 1 page in session history and Shift + Backspace will navigate forward 1 page in session history.

1 - Pressing Backspace will scroll the page up in the current document and Shift + Backspace will scroll it down.

Any other positive integer (2 or more) will unmap the backspace key, which is what you want. But keep in mind, the integer data type has a limit, so don't got crazy. 2 will be fine.

• Type about:config into your firefox browser
• type in "backspace" in filter
• double click "browser.backspace_action" change the value 0 to 2.