How Receivable Account gets derived for a Credit Memo of source Order Management

Hi

We have few Credit Memos in Receivables Applications which was imported from Order Management. Now for few Credit memos we have Receivable Account derived from the Autoaccounting but for few credit memos for the same customers is getting derived something else. Suppose Autoaccounting has Receivable Account setup as 218.XXX.XXX.120.XXX.XXX.XX. But in few credit memos for the same customers, receivable account is getting derived as  218.XXX.XXX.121.XXX.XXX.XX. I checked the customer setup, Sales Channel Code is defined as Intercompany. In the transaction type setup, receivable account is defined as 218.XXX.XXX.121.XXX.XXX.XX, in the customer bill to site, receivable account is setup as 218.XXX.XXX.121.XXX.XXX.XX.