Just like the PO and Invoices module, you cannot make changes to a Payment if:
 1. You are not the owner of the Payment; or
 2. The Payment is in a non-editable status (PA, PD, RL, E, SE, or EX)
Not the current owner: If your name does not appear in the owner field located in the header of the Payment, then you are not the current owner and will not be able to make any changes. Select your name in the Owner field to begin making changes to the coding of the payment.

Non-editable status: Payments cannot be edited once in PA, PD, RL, E, SE, or EX status. To make changes to a payment in A or E status, you'll need to reset the payment in the details view of the payment.

If the payment has already been released, you'll need to revoke it if the option is available. Any status past RL cannot be changed.