Hi Too
Check the link.
https://help.sap.com/saphelp_sbo882/helpdata/en/45/07edb6ae742461e10000000a1553f7/content.htm
Use Negative Amount for Reverse Transaction
Selecting this option results in journal entries where the reversal is booked with negative amounts. If you do not select this option, the journal entry of the reversal is booked using a debit/credit switch. This setting can be changed at any time.
Regards,
Kennedy