yes Trabis ...

that solves it.......i replace it with 4

now the permission is correct....
as example even though i can see the group setting icon..i cant access it

so is this problem can be categorize as a bug ?

I think that webmaster group should not have checkboxes for system permissions since they are hardcoded and cannot be deactivated.
They cannot be deactivated/removed because you could loose access to add them back again.

I don't know if I should consider this a bug because it is behaving as the developer wanted it to behave. My opinion is that this behavior is wrong, system permissions for webmaster group should not be changeable.