Good morning, @AEppley. 
 
Welcome to the Community! I'd be more than happy to show you your options of what you can do with a customer overpayment in QuickBooks Online. 
 
You have three options that you can choose from: 
 
 - Apply the credit to an invoice. 
- Refund the customer for the overpayment. 
- Record the overpayment as a tip. 
 
For more details on how to perform these specific actions, review this guide: Handle a customer credit or overpayment in QuickBooks Online. 
 
Keep me updated on which option you choose and if it works for your business for the overpayment you received. Happy Monday!