If you have already filed your tax return then you need to amend your tax return if you need to make any changes.
First, make sure that the original tax return has been accepted and any refund that you are due or amount that you owe has already been processed. Then, log in to your TurboTax account and click the 'amend' button on the return that you already filed. Make any changes that you need to and then file the return.