If you wish to amend, download your tax return now into a .ta2016 file on your computer. You will need it.
It also helps to have a good paper copy of the tax return as originally filed.

You will need to amend the 2016 tax return to add the capital loss carryover.

See this TurboTax support FAQ for amending a 2016 tax return originally completed using the online editions - https://ttlc.intuit.com/questions/3402261-how-do-i-amend-my-2016-turbotax-online-return

Do not start the amend process until you have received the 2016 tax refund or the 2016 taxes owed have been processed by the IRS.

If the link to amend the 2016 return is not showing in the 2016 Timeline under Some things you can do:  Then go to this website for the 2016 amend software - <a rel="nofollow" target="_blank" href="https://turbotax.intuit.com/personal-taxes/cd-download/amend/ty16/">https://turbotax.intuit.com/pers...>