How to assign bank debit entry to correct invoice?

Hi, since we have a lot of different payments (debit entries) in our bank account which need to be assigned to the correct invoices, I'm currently very desperate. Adobe mentions some number in the debit entries, but this number is nowhere to be found on the invoice nor anywhere else. So how can I know, which payment on my bank-account is concerning which invoice? What is the meaning of the number on the debit entries? How can I relate it to the correct invoice?