How to Edit User Group Permissions
You can assign permissions to individual users as well as all users in a group. The permissions of a group member consist of the permissions of the individual user and that of the user group he belongs to.
Important: You cannot edit permissions for the [Default Group].
Example: How Do User Group Settings Affect Individual User Permissions?
On the user permissions page, permissions inherited from the user group are marked with a symbol next to the permission's name.
You cannot change these permissions at the individual user level.