Firefox for iOS gives you the option to change your default search engine. Here's how to do it:
Tap the menu button at the bottom of the screen (the menu will be at the top right if you're using an iPad):
- Tap in the menu panel.
- Tap .
- Tap the current default search engine to change it.
- Tap the switch next to the search engine you want to turn it on .
- After you select a new default search engine, Firefox will take you back to the Search screen. Tap Settings to return to the menu, and tap Done to close it.