All the forums and subforums are displayed on the same forum display
 

How do I make sure that there is a distinction between forums and sub forums?

http://intdex.com/forums/index.php

Is it just because of the style because the default style is very weird.......... it just shows everything without showing any difference between categories, forums & sub-forums. In this case, I edited the main category to be "Linux" but it shows up at the top.