You're always welcome and thank you for getting back to us here on the Community page, @OlAl.

Allow me to share additional insights about customer credits in QuickBooks Online.

There may be credit memos recorded for that specific customer reason why they show up when recording invoice payments. If you wish to, you can visit the Audit Log to check for those transactions.

Here's how:

1. Select Audit Log from the Gear icon.
2. On the Audit Log window, click on the drop-down arrow beside Filter.
3. Filter the users and the period of transactions you want to see.
4. Click on Apply.
5. Once completed, scroll-up/down the page to review the credit memo/s added, and who recorded to QuickBooks. If you wish to have a detailed view of the transaction/s, click on the View link under History.

Also, you can check for the customer's unapplied credit memos by following these steps:

1. Go to the Sales menu at the left pane, then select Customers.
2. Click on the customer's name you want to open.
3. Go to the Transaction List column, then filter the transactions to Credit memos.
4. Tap Apply.
5. You can open each transaction, and if you think they shouldn't be recorded, you can click on the Delete button from More.

As always, click the Reply button if you have any other questions. I'm happy to help. Wishing you continued success!