To set default notes/terms in packing list, please follow the path bellow:
Step 1: Click on Invoices under Sales, and click on Document Settings.
Step 2 : Click on +Add Notes & Terms.
Step 3: From the dropdown, select Packing List.
Step 4 : Click on +New Packing List Notes.
Step 5: Enter required notes/terms and click on Save.
Step 6 : Enable default option and click on Save.