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In case when it is necessary to change debt between Customers. In Accounts Receivable use the button Pick for choosing the receivable document i.e.
Invoice.
Accounts
In the Payee attributes, make sure to choose the Credit note document.
Accounts Amount and Accounting Amount in Accounts Receivable and amount of Settlements and Accounting Amount in the Payee Attributes should be matched.
Choose the right contract. On the 2nd and 3rd tabtabs, they must match.
Select the document Advances Received from the list.
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Post and close.
Generate a report on mutual settlements for verification and you will find that balance are already offset.
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