You cannot amend a tax return until after the return has been filed and accepted by the IRS or the State.
You complete your tax return by finishing all 3 Steps in the File section. In Step 3, to e-file your tax return, you must click on the large Orange button labeled "Transmit my returns now".
After completing the File section and e-filing your tax return you will receive two emails from TurboTax. The first email when your tax return was transmitted and the second email when the tax return has either been accepted or rejected.
An amended tax return, Form 1040X, can only be printed, signed, dated and mailed by you to the IRS, it cannot be e-filed. The IRS will take up to 4 months to process the amended tax return. Wait until you have received the tax refund or the taxes owed have been paid and processed by the IRS before amending the tax return.
To access your online tax returns sign onto the TurboTax website with the User ID you used to create the account - https://myturbotax.intuit.com/
Scroll down to the bottom of the screen and on the section Your tax returns & documents click on Show. Click on the Year and Click on Amend (change) return
See this TurvrboTax support FAQ for amending a 2019 tax return - https://ttlc.intuit.com/community/tax-topics/help/how-do-i-amend-a-2019-return-in-turbotax/01/123845...
Amended returns cannot be e-filed. If you have prepared an amended return you have to print, sign and mail it. However, the IRS is not even opening mailed returns at this time; if you mail it soon it will end up sitting in a pile of unopened mail in a trailer. Sometime later in the year (we do not yet have a date) the IRS will start to allow e-filing of amended returns. You might want to just wait for that. You have three years to amend a return.