How much do I enter on line 34 of Form 540 if it says Total Donations from SchD of $48 plus overpayment credited to next year is more than $3.00 available

It says please reducers your contributions or overpayment credited to next year so the total does not exceed your overpayment of $3.00. Each time I try to reduce box 34, it refreshes back to the original entry.