Problem
You are unable to apply credits from two voided invoices to another invoice in ServiceTitan.
Solution
Find and go to the invoice where you want to apply the payments.
Click on Collect and Apply next to the charge.
Select Save without charging from the dropdown menu.
Enter the amount you want to apply.
Click Save.
If you receive an error message when using a credit card payment type, try using a different payment type.
To reflect that the invoice has been waived, add negative payments on the adjustment invoices so that the negative balances become 0.
To add negative payments, put a negative task to remove the tasks of the invoice and negative payment of the same amount to also void the payment that was made on the invoice.