Payments and Invoices reports will give you detailed information on the payments from your customers and the invoices status:
To access these reports, go to menu 'Intelligence':
And click on the report you are interested in:
Payments: List of the payments from your customers.
Overdue Invoices: List of all the Invoices that are past their due date.
Unpaid Invoices: List of all the "unpaid" or "partially paid" invoices.