The page with the field I am not able to update is 10 screens later, "Enter Payments You've Already Made." That is where I am not able to update the "Federal Income Tax Withheld Learn More" field. It is grayed out and does not allow updates. It carried over what I entered on the first page (my entire estimated tax withholding for the year), but it should be allowing me to enter what has been withheld year-to-date.
