We use a custom theme for our forums.
We think it lays out better but we recognize that not everyone sees it the same way!
If you prefer to use the default theme that is provided by the great folks at Xenforo,
we have left that as an option.
Simply scroll down to the bottom of any of the forum pages, and click on the title of the theme in the bottom left corner of every page. That will bring up a Style Chooser, where you can change the theme by clicking the name of the theme you would prefer.