Entering Received Customer Payment without an Invoice

Good day to you, @afsmith. I''ve got some options about how you can record your customer payments in QuickBooks Online (QBO).

First, if the payment is for your sales, you can either create a sales receipt or record a bank deposit transaction for income.

The second option is to create a credit memo or generate a bank deposit affecting Accounts Receivable (A/R) if you want to apply your customer's payment to their future invoices. 

Also, before creating a credit memo, please make sure the Automatically apply credits feature is turned off so that the credit won't apply to any open invoices. You can read through this article for more information: Create and apply credit memos or delayed credits in QuickBooks Online.

Furthermore, if you've linked your bank accounts to QBO and the transaction shows up in your bank feeds, you can simply match it to the sales receipt or bank deposit you've recorded. Here's an article for your reference: Categorize online bank transactions in QuickBooks Online.

I'm just around the corner to provide additional assistance to help you manage your customer payments in QBO. Have a good one, and stay safe.