You would need to amend your 2021 tax return if it was filed incorrectly. You will see an option to do that on your home page when you log into TurboTax. Look at the bottom of the page, under Your Tax Return and Documents. Click on the year you want to amend and choose the Amend (Change) option.
If you mean you need to correct the cost basis reported on an investment sale, you will need to edit that sale in the Investment Income section of TurboTax, then Stocks, cryptocurrency, Bonds, Mutual Funds, Other.
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