Regions permissions are inherited from the title where they belong.

To grant to users the permission to view and select regions, the Everyone group must have at least the View permission.

IMPORTANT: Pay a special attention on denials! If a user belongs to more groups, certain permissions may be denied on the level of another group and if the group has a higher priority of the one you're looking at, you won't see the denial, but it will be effective. Note also that denials may exist on the personal level too.