That's not true. I called the IRS and the agent confirmed that I can override the field.  The agent confirmed that stimulus 1 and 2 payments were based on 2019 taxable income.  When filing to recover the amount on 2020 return, they will verify the amount against what was paid and not paid and will issue the amount along with the tax refund accordingly.  I ended up paper filing the form for the client to recover the amount due to her.