Is there a report to indicate whether or not credit memos have been applied or unapplied?

Hi there, @anna54.

I'm here to ensure you're able to get the report that contains credit memo status in QuickBooks Online (QBO).  

Yes, there's. We can run the Transaction List by Customer Report in your account. I'm happy to provide steps and screenshots to achieve this matter. 

1. Go to the Reports tab on the left side, then type the said report in the search box.
2. Click Customize button on the right side. 
3. Pick accurate Report period in the drop-down arrow. 
4. In the Group by, choose Transaction Type, then check the Customer, Open Balance, and Amount box. 
5. In the Transaction Type field, select Credit Memo and Payment. 
6. Choose the customer's name in the box.
7. Tap Run Report. 
8. Review the Payment description if add notes. If there isn't, you may click the amount to see the applied credits.

For more details about customizing, visit this link: Customize reports in QBO.

You can also tap the Save customization button to memorize the report. This will help you save time since it automatically updates every time there are newly added transactions. For more details, check out this article: Memorize reports in QuickBooks Online.

I've also added some articles about handling credits and different reports. 

• Create and apply credit memos or delayed credits 
• Reports included in your subscription

Feel free to let me know in the comment section if you have additional questions about memos. I'm always willing to help. Take care always.