[zascok]

Newbie1, all you have to do is create a separate userGroup lets say "noClowns" or groups "noClowns1" "noClowns2" etc

Then you create a forum /forums lets call it "notCircus" "notCircus2" "notCircus3" etc

When done open the forum's)each one individualy) permitions and edit the user groups right (to see, to write etc)

After you done assign moderators for the "notCircus" forum/forums

And finaly you might grant the permision to become "noClowns" to users: manually or trough promotion or trough subscription.

About the moderators, make a user of forum a moderator of forum but don't move them into Moderators usergroup or Create separate usergroup "ModsForNoClowns" edit the usergroup rights and don't forget to edit the forum permissions as well

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Also you might wanna to read a little bit in mans
https://www.vbulletin.com/docs/html/forums_moderators