When you setup a vendor in AX you will have to make a determination about how you view the accounts payable for that vendor in the general ledger. For example you might want to see specifically accounts payable to a specific key supplier if it’s large or strategic. Or this might be at a group like for a collection of suppliers. This is possible via the vendor posting profiles. These are what is then used to find the accounts payable account when you are doing transactions as the default account for that vendor for example when you do a vendor invoice or purchase invoice. This is a quick walk through the setup.