Sales Invoice - "Due Date" vs "Payment Due Date"?

Please help me as I am getting 2 different Due Dates values for a Sales Invoice in 2 different reports

  1. Sales Invoice List
  2. GL Entry Report

When I open a particular Invoice Payment Due Date is ONE value which is used in listing Sales Invoice list

But

Another Due Date is used in GL Entry List that is written in the Payment Template.

Please help me with correction & also guide how get DocStatus back to Unpaid from Overdue if real Payment Due Date has not arrived.