How do I change the permission set for a code group? Can i??????

Yes u can, use caspol. If you are the machine administrator, you can operate at the ‘machine’ level – which means not only that the changes you make become the default for the machine, but also that users cannot change the permissions to be more permissive. If you are a normal (non-admin) user you can still modify the permissions, but only to make them more restrictive.

Note that because this is more permissive than the default policy (on a standard system), you should only do this at the machine level – doing it at the user level will have no effect