When I log in as admin, the home page shows all the categories and forums. When I log in as someone else, the home page only says, "This board has no forums." Why can't anyone else see my forums? http://3d-rad.mutluforums.com/

I believe you would need to post a testing/admin account so the helpers can see the homepage without registering.

But for now, you can check the permissions of the forum/categories and make sure, members can see the forum/categorie.

I already had the permissions set to all. I can search a topic and the forum posts will show up. But I can't just go to the forums on the home page. It says "This board has no forums." What does it mean to post a "testing/admin account" and who are the "helpers?" I don't know what you are talking about.

I actually only wanted you to post an account so the moderators (of this forum - can probably be called as 'helpers', too) don't have to registarte on every site where problems occur.
So they can take a look since you need to log in before you can see anything. But it's up to you.

For you problem: Have you only categories? Or did you add a forum to each category? Because if you create a categorie without a forum, it won't show up.

Some where on your forum you have it set so only admin and/or mods can view that certain forum so go back through and see what you can fix and if you cant find nothing comeback and make me a guest account so i can see what you mean.

I had all the forums set to all, but they were under "Basket" which I never touched and was automatically set to admin only.