Installed firefox browser in your android mobile and set this browser as default browser. If you want to change your browser settings than you should have to follow these steps to restore browser settings.
Visit Settings > Applications > Manage applications
Or
Visit Settings > Applications > Downloaded or All Applications
Now find the browser you now have as default and find "clear default" option and click on "Clear defaults" in the details page, then go through the process described in the first paragraph.
Your browser setting restored to default .
