How to change Language in Firefox interface to English

I installed Firefox in French,how do I switch it to English? If you have the Firefox user interface (menu bar) in the wrong language or want to change the current language then you can get Firefox in the language of your choice here: http://www.mozilla.com/firefox/all.html Uninstall the current Firefox version, but make sure that you do not remove your personal data. Install the new Firefox version of the wanted language.