The Debt screen is only intended to capture the basic terms of the debt and to possibly schedule its future payoff (an option available in the Advanced Settings).
Whenever a debt is entered into a plan, a debt payment expense is created for it automatically. It is this payment expense, not the debt itself that can be adjusted to schedule future increases or decreases in debt payments.
Click the link icon beside the debt in the ledger.
Two items may be shown as linked to the debt: a property (if this is a mortgage) and a "Debt – payment" expense.
These items are active links that can be clicked to jump directly to the details either about the home, on the Property/Assets screen, or the future debt payments, which are scheduled and managed on the Expenses > Basics screen.
How to increase or decrease mortgage payments
To schedule an immediate increase or decrease in mortgage payments, simply edit the starting mortgage payment on the Expenses > Basics screen.
Future payments can also be stepped up to plan for future over payments or reductions in payments, perhaps after refinancing.
Payments can be stepped up or down (increased or decreased) by event or stage using the Basics screen's Step Up / Step Down feature.
To ensure that any future stepped amounts are not inflated values, expand the Inflation panel and select Future Value.
Normally with expenses it is best to leave this at the default, Present Value. In this case, however, the Future Value will ensure that the 'stepped' mortgage payment amounts will be applied exactly as entered and will not be inflated using the inflation rate, above, as will occur whenever Present Value is selected.