To change the default search engine in Mozilla Firefox, follow these steps:
- Open Mozilla Firefox.
- Click on the three horizontal lines in the top-right corner of the screen.
- Click on "Options."
- Click on "Search" in the left-hand menu.
- Under "Default Search Engine," click on the drop-down menu and select the search engine you want to use as the default.
- Close the "Options" tab.
Your new default search engine will now be used whenever you search in the Firefox search bar or address bar.