Can't change New York State tax payment date on line

I filed my tax return a month or two ago, and originally scheduled my payment to NY State for April 3, 2021.  I cancelled that payment and want to reschedule the payment date to May 17, 2021, but when I go to the NY State Tax website, it will not allow me to schedule my payment for any date other than the default April 15, 2021 date.   How can I now schedule my payment date for May 17, 2021?  I tried calling NY State and they said they had no answer.   Does anyone know what's going on?