Through the settings of purchase orders, you can add a default note that will be displayed on the PDF of your purchase orders.
1. Go to the Purchase Orders submenu of the Orders & Deliveries module. Click on the Settings Purchase Order Settings and then choose "Notes". Here you can now add a default note that will be displayed on the PDF of your purchase orders.
Tip At the top, you can change the language of the note.
2. When creating a purchase order, you can view and/or modify this default note by clicking on "Notes" at the bottom of the creation screen.