How do payment terms from Pallet Connect transfer to Quickbooks? 

When an invoice is imported from Pallet Connect into Quickbooks, it will also bring in the terms for that invoice. 

Having Pallet Connect set the due date is by design. Just like adding an invoice in Quickbooks directly, the due date can override the date set by the payment terms.

This is also important because if an invoice is sent from Pallet Connect, it should match information the customer received.

It is recommended practise to enter payment terms for customers, in the "Invoice details" tab of the contact profile.  Also to make sure they match the term types that have been set up in Quick Books.

See related articles on setting up payment terms.