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.
All Invoices: List of all your Invoices. You can filter on 'Unpaid' or 'Partially paid' to help you follow-up with your customers.
Overdue Invoices: List of all the Invoices that are past their due date.
Invoices per user: List of all the Invoices created by one user.