Hi
Configuration for the Payment method supplement (PMS) is done here:
Financial Accounting >AR/AP>BT>Outgoing Payments>Automatic Outgoing Payments>Payment Method/Bank Selection for Payment Program>Define Payment Method Supplements
However the defaulting in the document happens based on the settings from FBZP in set up all company code for payment transaction - If the check box "Pyt meth suppl." is checked, then it defaults the PMS. However, you can overwrite the same.
Thanks
Srini