Account Code Format: the default code format is 'AAA-AAAA'. You may set your own Account Code format; you can even use free format. Should you change the format after creation of accounts, the earlier account codes will remain in previous format; to change the account code, go to Tools > Change Code > Change Account Number.
Automatic Generate Debtor/Creditor Code Format: this is to set the format of auto-generated debtor/creditor code. The format of debtor/creditor code need not be the same as that of Account Code.