I'll guide you on how you can change the due date on the actual invoice, Heather. 

One of the main reasons why it's important to set a due date on an invoice. This is to encourage your customers to pay you within a certain period of time.

On the actual invoice, you can simply edit the field to change the due date. I've added this screenshot for your reference:

Furthermore, learn how to create custom templates and customize them so you can control how they look and what information to include. I've added this article for more details: Use And Customize Form Templates.

Leave your comment if you have any questions about invoices. I'd be happy to help.