MyBB Community Forums

When guest visit my forum, they see the default MyBB theme. When they login, they see the MyBB theme that I customized (I customized the default theme).
This is my forum:
http://termsofsinnoh.co.cc/forums

If you want to make the guests see the customised theme, you need to set it as default in the ACP (on the themes page)

It is the default theme.

In the theme do you have it set that all user groups could see it or did you select a few?

Set to all groups.