I assume you mean you had foreign tax credit carryforwad from your 2016 to your 2017  and 2018 returns.  If you have excess foreign tax credits, you can carryback one year and then forward 10 years. You can utilize them to help offset business trips overseas, etc.  The carryforward tax needs to be in the same category as the foreign income you have this year.

Just enter the foreign tax credit carryovers in TurboTax.  In the Search bar at the top screen in TurboTax , enter foreign tax credits and then ciick on the "jump to".  The carryovers are input near the end of the foreign tax credit section.
 

Thank you but this is not answering my question.  I am purely asking if I have foreign tax credit in my 2016 filing and forgot to input it again in 2017 or 2018 filing, can I just input it as carry forward in my 2019 filing or do I need to refile 2017 and 2018.  I AM NOT using the credit, just carrying it forward.

thanks

You will be required amend your 2017 return. You would enter the 2016 Foreign Tax Credit carry forward on the return to determine the amount of the credit to be carried forward to 2018. The 2016 carry forward will be on the 2016 Form 1116.  

You would then amend your 2018 return. You would enter the 2017 Foreign Tax Credit carry forward on the return to determine the amount of the credit to be carried forward to 2019. The 2017 carry forward will be on the 2017 Form 1116

You will then use the 2018 Form 1116 to enter the information on your 2019 return.

If you do not do the amendments, the IRS will eventually question where the carry forward came from on your 2019 return.