Default Terms
If you set your Default Terms up on the Company Record it will be remembered through to the quote, order, vendor bill, etc.
This drop-down choice automatically sets the due date on customer (receivables) and vendor invoices (payables) once the invoice date is set (if the Invoice Due In Day(s) is set accordingly in the Terms of Sale drop down by your administrator as shown below).
See Drop Down List: New Terms of Sale on how to setup a new set of Terms and Payment Schedule.