Warm greetings, Brent. I'm here to provide you with some insights into the overview invoices.

When you have overdue invoices from 2018, 2019, and 2020, it won't show in the Overview Invoices section; the as of today indicates the latest overdue invoices dated and their total amount. See the attached screenshot for reference.
 

As previously mentioned by my colleague, the Customers section displays a summary of all overdue invoices, including past invoices linked to the specific customer. 

For future reference, if you've received a payment from your customer, it's important to record it in QuickBooks. It will mark the invoices as paid and will make it easier for you to track your outstanding and paid invoices.

I'm still around whenever you need clarifications regarding the overview invoices feature and if you need help managing your invoices. I'm always here to support you. Best wishes!