What is Inheritance 
The most important concept in vBulletin’s permission system is inheritance. In vBulletin a new usergroup on your site can inherit the permissions you have already established for another existing usergroup. In the new usergroup you can then override any permissions you want to be different from the original.

In vBulletin there are two levels at which you can specify usergroup permissions.

Global Permissions
The first is at a the global level, which applies to all channels on the site. To edit global permissions, go to Usergroups > Usergroup Manager > Edit Usergroup.

The permissions you specify at the global level apply everywhere on on your site unless you override them at at a lower level (for example, at the channel level).

Channel-level Permissions
To edit channel-level permissions, go to Usergroups > Forum Permissions. Permissions you specify for a channel are automatically inherited by any child channel, unless overridden for the child channel.
User Contributed Notes: What is Inheritance