That's not how phpBB permissions work though.
A user could have permissions assigned by their role or any of the groups of which they are a member (or, you can assign permissions to individual members). If ANY of these groups or role have a "Yes" permission, then that user will receive that permission.
If ANY of those groups or roles has a "Never" permission, then that will override the "Yes" to become a "No".
So you need to set it for the member OR the group OR the role, not all.
This is the same as opening any forum to a group, or locking one down.
WP-United just uses the native phpBB permissions system, and doesn't impose any additional requirements on top of that.
phpBB MODs usually aren't allowed to turn on permissions by default -- people are encouraged to review and amend the permissions themselves. I will certainly do what I can to make it clearer though.