Whether a member can open a category, start a topic in it, or read the topics inside it is decided by two separate permission layers, and changing the layer that is not in charge has no effect. This article explains how the two layers work together and how to tell which one is deciding.
The two permission layers
Which permission layer applies to a category?
There are two. The first is the user group's own default permissions, which you set for the group as a whole from User Groups (open the group's Manage menu and choose Permissions). The second is a set of custom permissions for one specific category, which you set from Categories (open the category's Manage menu and choose Change Permissions).
When a category has custom permissions of its own, those decide for that category and the group's default permissions are ignored there. When a category has no custom permissions of its own, the group's default permissions apply, unless the category inherits from a parent category as described below. The article Setting a user group's category permission walks through the per-category dialog, and Editing a user group's default permission walks through the group-level page.
Does a category with no custom permissions of its own follow its parent category?
Yes, when a parent category has custom permissions. A category with no custom permissions of its own inherits the custom permissions of the nearest parent category that has them, so its behaviour follows that parent rather than the user group's defaults. Only when no category in that chain has custom permissions do the user group's default permissions apply.
This is the usual reason a sub-category behaves differently from a user group setting you changed: the sub-category is following a parent category's custom permissions, not the group.
Checking and changing the layer in use
How do I see which layer is deciding for a category?
Open the category from Categories, choose Manage and then Change Permissions. Above the permission list the dialog names the layer in effect for the user group you are viewing:
- Custom permissions for this category when the category has its own custom permissions.
- Inherited from the parent category followed by the parent's name, when the category follows a parent category's custom permissions.
- Inherited from the user group's default permissions when no category in the chain has custom permissions.
If the category has sub-categories, the dialog also warns you when they would end up with different permissions from the category you are editing.
Why did my permission change have no effect?
In most cases the other layer is in charge. Turning a permission off for a user group does not affect a category that has, or inherits, custom permissions, and setting custom permissions on a category does not affect a sub-category that has custom permissions of its own. Check the layer named at the top of the Change Permissions dialog first, then change that one.
Permission changes take effect the next time the member loads a page. Members do not need to sign out and back in.
How do I make a category and its sub-categories match?
Open the category's Change Permissions dialog for the user group and set the permissions you want. If a warning appears below the permission list saying that sub-categories differ, click apply these permissions to all subcategories. That removes the sub-categories' custom permissions so they follow the parent category, and the warning disappears once they match.