https://support.mozilla.org/en-US/kb/add-or-remove-search-engine-firefox https://support.mozilla.org/en-US/kb/how-to-set-the-home-page

''<p>Judy [[#question-1418782|said]]</p>'' <blockquote>I want my Firefox to use google as my search engine. I do not like yahoo. </blockquote> The Firefox web browser from Mozilla.org has not come with Yahoo as one of the search engine defaults since late 2017. https://blog.mozilla.org/en/mozilla/mozilla-files-cross-complaint-against-yahoo-holdings-and-oath/ So perhaps you installed the Yahoo search engine yourself or one of the Extensions you have installed in Firefox has inserted a Yahoo search engine in Firefox, has occurred before. Or worse case it is due to some malware. https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware