Hi MattBedford​ and Elisem​
When an invoice is paid via online payments there are two transactions created automatically in the process. These work a little differently to how manual invoice payments are recorded.
First, we record a payment on the invoice to close it so it can't be paid again.
This goes into the undeposited funds account
Second, when the money is deposited into your actual bank account, we record a deposit transaction that moves the money from your undeposited funds account into your cheque account (or whichever account you have selected as your payment category).
This deposit transaction is what prevents the invoice payment from being edited - the invoice payment is included in the deposit transaction and therefore can't be edited.
As long as your online payment categories are selected correctly these will balance in the end and you should not need to record any manual transactions yourself.
More details on the transactions that are recorded during the process are documented in this help page.
