Forum duplicate permissions access problem
 

My forum is private now and I have setup all my registered members to only see the main forum without being able to post anything in any forums. I've done that setting the permissions in Usergroup permissions in the adminCP.

The problem is that they used to have personalized forum permissions access within the adminCP Forum access options.

Now, when I tried to remove their different forums access (because they are in red) by copying the permissions from one group (that does not have any rights or access at all,) to the registered members group, it fails. Well, it says that it does but my registered members remain unchanged.

I did check the Overwrite Duplicate Entries and Overwrite Inherited Entries to Yes.

I have over 350 forums and sub-forums and about 15 membergroups so I don't want to adjust these permissions manually.

Hw to resolve this problem?