Ya for "Firefox" it is easy just go to the Place you would normally type in your "WWW" and type "about:config".
click "OK" or "I'll be carefull" on the next screen.
Scroll down the next list and look for anything that says "Plasmoo" and replace it with "
http://www.google.com/search?q=".
Goto to top left corner and pull down menu and click close.
re-open and google will be your friend agian....