If you would like to add net payment terms, go to the client’s account and navigate to the Payments tab. From there, you can specify the number of days.
You can also include comments or any specific instructions on all your customers’ invoices. Navigate to the Portal, select the respective Organization and then add the Comments under Invoicing.
Alternatively, if you prefer to add notes on a per-order basis, open the individual order, go to Adjustments, and add your note there.