To set Ecosia as your default search in Firefox, visit this page and follow the on-screen instructions.
1. Click "Add to Firefox"
2. Click "Allow" in the Firefox dialogue box in the top left-hand corner.
3. In the same dialogue box, click "Install"
4. Finished! Ecosia is now your default search engine in Firefox.
All searches via your Firefox URL bar will now use Ecosia. Use Firefox's search bar to the right of the URL bar anytime you want to use another search engine. Make Ecosia your homepage or update extension settings in Firefox's Preferences panel.