Torbutton comes pre-installed with Tor Browser and we urge you not to change it. We do not recommend to install it to Firefox because this is not a sufficient way to surf anonymously. Torbutton guarantees that DNS requests are sent through the Tor instance that comes with Tor Browser. You should not change the proxy settings. It’s strongly discouraged to install new Add-ons in Tor Browser, because they can compromise both your privacy and your security. Plus, Tor Browser already comes installed with two add-ons — HTTPS Everywhere and NoScript — which give you a lot of added protection. You can read more about it here: https://www.torproject.org/projects/torbrowser/design/ Also have a look at this page for already answered questions: https://trac.torproject.org/projects/tor/wiki/org/teams/CommunityTeam/Support_discuss For other issues you should know about have a look at this blog post: https://blog.torproject.org/toggle-or-not-toggle-end-torbutton For a list of all torbutton announcements see https://blog.torproject.org/category/tags/torbutton