Change Customer Account to Capricorn
Once there is a transaction on the account, you can't just change the field in Customer Maintenance.
you can however change it in Accounts Receivable > Maintain Customer Account Details > Code Conversions > Bill-To Code Conversion.
This will also move the transactions over with it. however, please note, if you have already done your Caplink for the day of that sale, it won’t add it to your Caplink retrospectively. so, you will have to advise Capricorn manually of the transaction. If you haven't yet done that Caplink, it will go through it normally.