To change Firefox address bar search to google search do as follows:-

1. At Firefox address bar, enter about:config and press ENTER.
2. At Filter: field, type keyword.url
3. You should see a Preference name of keyword.URL in the list. Double click it, Enter String Value input box will appear.
4. Replace the string with: http://www.google.com.my/search?q=
5. Click OK button and you are done!

If you want to set Firefox address bar search to Google's "I'm feeling Lucky":

1. Type about:config in Firefox location bar and pressEnter.
2. Type keyword in Filter textbox and you will see only the preference keyword.URL.
3. Double-click on keyword.URL and change the value to: http://www.google.com/search?btnI=I%27m+Feeling+Lucky&q=