Click the X button next to the payment and materials to remove them and clear the invoice.
Create a new invoice under the correct customer.
If a customer short pays an invoice and you don't want to worry about the balance, adjust the task amount for the time being equal to the underpayment.
If the invoice was already batched over, unbatch the invoice, add the task amount for the underpayment, then re-Batch the invoice.
A batch, or invoice batch, is a set of invoices that have been audited and are ready to post. You will use the Invoice screen in ServiceTitan to create invoice batches. On the Invoice screen, you'll have access to unbatched and batched invoices.