Payments Received recorded now want to assign to invoice

We received an unknow payment so recorded it as "Receive Money". We now know which invoices to allocate this payment to but am unsure how to do this? 

When going into Receive money and we type the name of the "Payor" we receive the warning "If the deposit you are entering is a payment for a sale that you have recorded, you should be using "Receive Payments" instead of "Receive Money".  

However am unsure how to link payment to invoice in "Receive Payments"

Please help!!