Hi, TAC.

It’s currently not possible in QuickBooks Online. You can only see the invoice number in the Receive Payments screen. As a workaround, you can manually enter the PO number on the memo field at the bottom.

You can also send feedback to our developers requesting to show PO number in the Receive Payment screen. Just click the Gear icon and select Feedback.

Please do not hesitate to get back to us if you have further questions about QuickBooks.