Why can I not amend my 2018 tax return?

[0215car2017]

I see my 2018 return but I am unable to follow the instructions on downloading TurboTax Desktop 2018 for Windows.

[DoninGA]

See this TurboTax support FAQ for amending a 2018 tax return originally completed and filed using TurboTax - https://ttlc.intuit.com/community/amending/help/how-do-i-amend-a-return-in-turbotax/01/27579

If you used the TurboTax online editions to complete and file the 2018 tax return - 

To access your current or prior year 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 2018 and Click on Amend (change) return and Click on Download .tax file

[DoninGA]

NOTE - If you paid for one of the TurboTax 2018 online editions then contact TurboTax support and they can push a 2018 desktop installation file to your download account at no charge -  https://support.turbotax.intuit.com/contact/

Otherwise you will need to purchase and download one of the 2018 desktop editions from this website to amend the 2018 tax return - https://turbotax.intuit.com/personal-taxes/past-years-products/