Creating PO from MD04

When creating a PO from a PR in MD04, the default purchase order type is not holding the user personal settings. We have one type of purchase requisition, ZZNB and 2 types of PO's. ZB and ZZNB (distribution and trade respectively). When the user tries to create a PO from MD04, it will default to the same type of PO, ZZNB. User personal settings are ZB and paramater DOCTYPE is set to ZB, but the system still defaults to ZZNB. This does not happen when creating a purchase order with ME21N from the requisition. It will hold the user settings. Is there something within MRP that needs to be changed?

Thank you .