Good day, @MasterImageWear,
There isn't a need to create a separate credit memo for the overpayment. QuickBooks creates a partial payment with a negative balance on the customer's transaction lists.
The next time you receive a payment, a credit will show up as Unapplied Payment on the Receive payment page.
If the Automatically apply credits feature is turned off, then you'll need to manually apply the credit when you receive a payment.
If the feature is turned on, QuickBooks automatically applies the credit to the next invoice. The status will then appear as paid or partially paid depending on how much available credits were applied to the total invoice amount.
This answers your concern for today. Please don't hesitate to post again if you have other concerns. We're always here in the Intuit Community to help.