How to Change Firefox Address Bar Search from Yahoo or Bing to Google
Firefox has a nifty little feature which doubles the address bar into very functional search tool. It’s very handy when you don’t know the exact address of any website. Let say, you want to go to the Wikipedia page of Microsoft, all you need to do is type “wiki Microsoft” into the address bar and it will run your text input through Google’s I’m feeling Lucky and takes you to Microsoft’s Wikipedia page.
That being said, it’s not always correct though. If it’s not sure about your query, it will simply take you to Google search results page for your query. But sometimes your address bar might change its default search engine with Yahoo or Bing without your knowledge thanks to some rogue application or erratic behavior by some Firefox add-on, and this can be very irritating since Firefox doesn’t provide easy way to change the default search provider of your location bar. If this ever happens to you, here’s how you fix it:
1. Open Firefox and type “about:config” (without quotes) and press Enter

2. Firefox will throw a witty caution message saying “This might void your warranty!” – Just hit “I’ll be careful, I promise!” button and move on

3. Use the filter text entry box to search for keyword.URL. Double click the Preference Name (keyword.URL) and paste Google’s I’m Feeling Lucky search URL – http://www.google.com/search?btnI=I%27m+Feeling+Lucky&q=

4. That’s it
You can use the same approach to change your search engine from Google to Bing or Yahoo.