samleung-
Lets try to simplify this and let me know if we are on the same page.
You have a button(Save) on the Bill screen and this button only has the Manager role checked.
You have a user(John), John only has access to the Staff role.
You have a user(Ralph), Ralph only has access to the Manager role.
When you log in as John and take a look at the Bill screen you shouldn't see the Save button.
When you log in as Ralph and take a look at the Bill screen you should see the Save button.
Is this how you have your roles set up? Also, are you viewing the copied screen you made and not the orginal?
-Michael