How to change Customer PO value on a Credit Order created from History?

Hi,

When creating a credit memo (P4210), if I retrieve the SO history by using the credit memo option under the Form exit and select the item, the original customer PO number from the history would overwrite the new customer PO number I entered on the credit memo. Is there a way to bypass the overwrite so I can keep the new customer PO number?

I searched the knowledge base and found a document mentioned that there is a workaround.

"In standard processing, the Customer PO field in the header is not available for editing after the Credit Memo Form Exit is taken to select a sales order from history. If a new Customer PO number is needed, enter the new value in the Add form prior to taking the Credit Memo Form Exit. The new value will be maintained and overwrite the original PO number on the sales order from history."