Firefox is a web browser while Bing is a search engine bing.com You can set whatever search engine you want as the default. Mozilla does not have their own search engine. https://support.mozilla.org/en-US/kb/add-or-remove-search-engine-firefox https://support.mozilla.org/en-US/kb/change-your-default-search-settings-firefox In case Bing.com or such is being set as Homepage. https://support.mozilla.org/en-US/kb/how-to-set-the-home-page https://support.mozilla.org/en-US/kb/wrong-home-page-opens-when-i-start-firefox-how-fix