I think your problem is in the understanding of Tiki permissions and Groups. When someone registers at your site, it means he/she automatically belongs to the group Registered. So everyone who registered is in Registered group and cannot be removed from it (otherwise they would be "Anonymous" visitors again). So when you give some perms to Registered group everyone who is logged in has it, regardless of other Groups you put them in (no matter if the other group has the permission or not). So your approach must be one of these:
- either do not give the global perms to Registered and give it to ROZOPS only ...
- or assign the gallery to the Category ROZOPS and edit the permissions of that Category to remove the perms from Registered group to override the global Groups permissions