I am trying to amend my 2021 tax filing as I received my corrected 1099 from from Robinhood, when I launch my turbotax desktop version on my Mac, I see option to "Amend a return (make changes) after it was filed and accepted by the IRS", on clicking that I choose "Yes, I have already filed my return" and "I need to amend my 2021 return" then it takes me to the page "what do you need to change on your return" but I don't see my existing filed return values to go and make correction, need instructions on how to correct the existing value submitted for stocks 1099-B. When I just update this income section, it considers the newly entered value as income and show heavy refund value, how to correct instead adding it as new value.
When you are in your amended return you should be able to click the "Search" option on the top right and enter "1099-B" then you can use the jump link. This should take you to your previous entries where you can click on "edit" to make corrections.
If this doesn't help then please see What is the TurboTax phone number?