Customer debts can be viewed directly on the customer account page or via the Aged/overdue debtors report.
Customer account page
If you head to Customers and select the customer you would like to view. If you then select Orders, credit notes & payments. You will see a full list of unpaid orders here.
Aged/overdue debtors report
This report can be accessed in Reporting -> Pre-built sales reports.
This will show you which customers have unpaid overdue invoices and how long the payments have been overdue. For a report on overall customer balances, you will be able to select the **Customer balance report **here instead.