How the due dates are reflected in the transaction depends on the terms that were set. You can create a new term and set it to 97 days to have a specific due date.
Here's how:
Open your invoice or bill, then go the the Terms drop-down list.
Click Add new.
Enter a name for the term, then set the number of days on the Due in fixed number of days.
Select Save.
I'd also like to share a few more guide articles and reference just in case you might need them in your future tasks: