Hello, smhonebrink. 

I want to ensure that you'll be able to close the invoices along credit memo successfully. Let's get this sorted out. 

First, we need to make sure you linked the credit memo and invoice so the invoice link to the credit memo will close. 

Then, it's not necessary to receive the payments manually. Once it's already linked, the credit memo will automatically zero out, and the invoice status show as paid. 

You can read this article for more information about applying credit memos and how to delayed credits in QuickBooks Online. 

In addition, you can also run the Customer Balance Detail report. This will let you see if the customer still has existing credits or balances. Just go to the Reports, and then type Customer Balance Detail. 

Fill me in if you have additional questions. I'm always here to help. Wishing you all the best. Stay safe!