restrict search help results on order types

I need to restrict search help results on the account assignment category for order type for the users when creating a SC. I have define fix values on the attributes PM_AUART & ANR & KNT (Order type, Order & Account assignment category) and maintained the related others PM attributes as well. But when I select the search help the system brings up all the Orders type and not the ones defined at the user attributes - PM_AUART (Order type). Do I am missing something? How can I restrict the search help when searching for order types?

Your support is highly appreciated.

Thanks

William