Hello,

1-Nothing is passed to the GL until you actually post a batch in AP that was created with the new AP Company profile settings. So past transactions won't update dynamically, if that's what you're asking.
2-The option you're looking for is on the "Batch/SystemCheck" tab in the AP Company Profile towards the bottom right hand side. This will then allow you to edit the description field on each line item in your AP transactions. If you type something in the Header Description field, it should automatically appear in your detailed description field on each line item. But you will be able to override it with that setting enabled.