Is there one report I can run that shows unapplied credit memo's by customer?

Yes, Gwessner. In QuickBooks Online, you can generate a report for unapplied credit memos by customers.

Let's pull up the Transaction List by Customer report and customize the data to ensure the unapplied credit memo will appear on the report page. 

Here how:

1. Click the Reports tab.

2. Enter the Transaction lists by Customer in the search bar.

3. Choose your report period.

4. Tap Customize and choose tick box Date, Transaction Type, Amount, AR paid, Customer Full name.

5. Next, go to the Filter section. Choose tick boxes Customer, Transaction Type, Equals, Credit Memo.

6. Press Run report. 

Based on the report above, your credit memos can have two statuses: unpaid means the transaction is unapplied, and paid indicates the payment has been applied to an invoice.

I'm including this page to assist you with customizing your reports in QBO: Customize reports in QuickBooks Online.

Moreover, you can consider exporting your reports to Excel from QBO. This allows you to customize your report in an advanced way: Export your reports to Excel from QuickBooks Online.

Let me know if you need to pull up another report for sales or expenses in QuickBooks Online. I'll be here to walk you through the process. Have a great day.