Why is Create Debit Memo turned on when I select Return for Credit on the supplier return screen?

Summary:

I am creating a return to supplier. I want to keep the PO line closed, because I do not expected a replacement. I expect a credit memo from the supplier for the returned item. I do not want to create a debit memo automatically, because that is not common practice in our country.

I do not understand why the Credit Debit Memo flag is set to Yes (and is display only) when I select Return for Credit. Why is the logic behind this? Why can't I turn this off?

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