To edit a paid invoice to either be applied to a different enrollment or to put the payment towards different charge items, you can follow these steps:
Click "Manage" on the Paid Invoices tab on the customer's Billing page.
Select "Edit" next to the Invoice you would like to adjust.
Select the three dots next to the charge (red line item) and click "Edit."
From there, you can edit which Program the charge is tied to.
You can also edit the Charge Item type and/or amount of the Charge Item. Under "Charge Items," select the down arrow to choose a different Charge Item or add Charge Items. The amount can be changed to any amount other than "0."
If you need to zero out the charge, the best option is to add a credit to the invoice with a public note explaining what the credit is for. When future invoices hit their account, the system will use that credit to pay the invoice.