I'll help you run those invoice reports you need. I'll also throw in an overview to help you understand what they are.
You can run the Accounts receivable ageing summary or detail report to show the unpaid or outstanding invoices within a certain period of time. This will also show what customer the invoice is associated with. Here's how to run it:
More details about the report can be found here: Run an accounts receivable ageing report.
Alternatively, you can run the Open invoices report to show those unpaid invoices. Though, this won't show you how long an invoice is overdue. Simply type Open Invoices in the search bar on the Reports page.
If you need help running reports in QuickBooks Online, this article can help you understand more about them: Run reports in QuickBooks Online.
Ready to process invoice payments after seeing your open transactions? Check out this guide on how to record them.
If there's anything else I can help you with, do let me know in the Reply section below. I can show you a thing or two on how QuickBooks Online works.