Bing is the default search engine on Amazon's Kindle Fire for browsing the net. But you can easily change it to Google or Yahoo! for searching the web. To set Google as default search engine on Kindle Fire, do as follows:
1. Open Silk Browser (The default browser on Kindle)
2. Swipe from the left edge to the right (or simply tap the 3 small lines icon on the top left) and tap on the Settings.
3. Under General settings, tap on Search Engine option
4. Select Google as your default search engine