I hate redirected searches
this sounds like a problem possibly caused by adware on your pc. please go to firefox > addons > extensions & remove any suspicious entries (toolbars, things that you have not installed intentionally, etc). also go to the windows control panel / programs and remove all toolbars or potentially unwanted software from there and do a full scan of your system with the security software that you have in place and/or a different tool like the free version of malwarebytes.
afterwards install the search reset addon - it will revert the most common customziations those adware programs do in firefox back to the default: https://addons.mozilla.org/firefox/addon/searchreset/