How can I know the amount of money entered into the company after the sale invoice is paid: total amount received per month from sales.

There is a report showing invoice and below the payment. but its time consuming to amend it and its confusing.

Noting that generated sales invoices in a given period may not be paid directly thus we need different report for total sales and for amount received from sales invoice. 

Is there a way to generate all payment made in a given period??