Granting members extra rights

We have the settings for our members as not being allowed to delete a post and they have only a limited time for editing. We have four members who need a bit extra, two set quizzes, the others give us updates on local bands and also the local cinema. We made them moderators, just on their own particular thread, but I have just realised that they can see who is on line when invisible and now I believe they have access to ban someone.

We need to set this up differently so that these four members can go back into their own posts and remove or at least edit them, without making this available to all members. I do not want them to be able to ban anyone, or have any other moderating powers, what is the best way to achieve this, if it can be done?

Anyone?

Hello,

Moderators = Anyone who can edit a post

• If you allow a moderator to "edit" posts, then they can edit posts forever - There's no time limit.
  
• If you allow Moderator's to ban, that means anyone that has right to moderate any forum can ban.
  
• Any moderator can see who's hiding in the "Who's Online" part of the footer if you allow the Moderator's to do, and the usernames are italicized when in hiding
  

There is no way to make someone a moderator if just 1 specific thread, or threads.
They have to be able to moderate that entire section, or not moderate at all

Thanks for your reply Darren, I will have to make them just members again. Is there no way at all that I can do that and give them them the power be able to go back & edit their stuff whenever they like, without giving that right to all members?