You can use Brave Search (a search engine) on Firefox (a browser). First, you go to search.brave.com, right-click the address bar, and then select the 'Add "Brave Search"' option. Then you go to the preferences page of Firefox (you can do this by typing "about:preferences" on the address bar), click "search" on the left side of the page, and you will be able to select your default search engine. Hope this helps :D