When you create a Payer, their Payment History begins with the transaction you used to save the Payer. If you find that there are additional transactions in your Payment Manager that do not appear on the client's Payer record, you can manually add them to the Payer.
Go to Payment Manager.
Locate the payment that does not have a Payer associated with it.
Click to view Payment Details.
Click Create/Add to Payer.
Select the correct Payer record.
Click Save.