Yahoo is a web search engine. Not a browser. https://support.mozilla.org/en-US/kb/how-to-set-the-home-page Type '''about:config'''<enter> in the address bar. If a warning screen comes up, press the '''I Accept the Risk''' button. At the top of the screen is a search bar. Type '''browser.startup.homepage''' What is the value? Right-click and select '''Reset''' to restore its default value; '''about:home''' ---------- Type '''about:preferences#search'''<enter> in the address bar. You can select any search engine to be your default from here. You can also remove any engine from here.