In the location bar, open the URL "about
:config". In the "Filter" section, type "backspace". Below that, you will see "browser.backspace_action". Double-click on that line, and a popup window will appear. Just type in "0" (zero), and click "OK". After that, your Backspace should be the way you want it.
From
https://answers.launchpad.net/ubuntu...+question/3578