Look for the Search in the address bar with option. Underneath that text, select the button labeled Change search engine. Choose your new default search engine, then select Set as default.How do you switch from Bing to Google search engine?
If you changed from Google to Bing or another search engine, it's easy to switch back to Google. To do so, open the Firefox browser and locate the menu button (three lines), then click on it. Next, scroll down to select Options and then click on Search.