Us old-time Windows bods get used to our keyboard shortcuts I’m afraid. One of the most useful is using the backspace key in the browser to go back through the browsers history.
Unfortunately, this is not the default under Linux (alt-left arrow is the default).
FireFox has an easy way to fix this. Put “about:config” in the address bar and “backspace” in the search entry. You should see the entry “browser.backspace_action”. Change this to 0.