How can I change my residency status

If you haven't filed you will be able to change your residency status by following the steps below.

1)    Sign into TurboTax Online.

2)    Continue your return by clicking Taxes > Tax Timeline > Take me to my return.

3)    Go to the Personal Info tab. On the Personal Info Summary page click edit next to your name.

4)    The next page will ask about your residency.

Hello - per the new 2020 tax change below need to specify that I'm a green card holder, not a US citizen. Where in turbo tax can I do it? 

"Failure to identify yourself a LPR on your taxes or accurately report your income may now lead to deportation. Note: If you use an accountant to prepare your taxes, he/she may assume you are a U.S. citizen. It is your responsibility to correctly identify yourself."

Currently, there is no such filed as residency status. 

This is not required, nor is there a field for it, on your 2019 tax return.  This is for the 2020 tax year.  So we will probably see a field for it on next year's return.