Yes, you can amend those returns in TurboTax for free. 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. You have up to three years from the due date of a return to amend it to receive a refund of prior year taxes.