"I'm thinking the program is broken.  I set all my customer to either net 60 or 90. The day after I create an invoice there's that stupid "Past Due" stamp on the invoice."

Did you confirm the due date, by looking at the invoice on your screen?

What did you set in your Preferences?

"Thank goodness I am able to set that to not print or I'd have some very upset customers.  I have done everything suggested and it still continues to show up the day after an invoice is created."

Edit menu > Preferences. You have over 360 setting here.

Go to Edit menu, Preferences, Reports & Graphs, Company Preferences. Here is where you control Age from Transaction Date or Age From Due Date.

From Transaction Date = the very next day = Past Due, or "How long has this been Out there?"

From Due Date = "how far past the due date is it still Not Paid?"