See this TurboTax support FAQ for amending a 2019 tax return originally completed and filed using TurboTax - https://ttlc.intuit.com/community/tax-topics/help/how-do-i-amend-a-2019-return-in-turbotax/01/123845...
There is nothing for you to check off for the child tax return. Either the child is eligible or not eligible based on the information you entered in the My Info section of the TurboTax program.
See this TurboTax website for CTC information - https://turbotax.intuit.com/tax-tips/family/7-requirements-for-the-child-tax-credit/L3wpfbpwQ
Go to My Info and verify your answers for each dependent entered.
Verify that you selected My Child, that the date of birth is entered correctly mm/dd/yyyy, (a child age 17 or older is not eligible for the CTC), that you indicated the child lived with you for the Whole Year, that the child did NOT provide over one-half of their own support, that there was NOT another relative in the home who also supported the child, that the child was NOT married, that you were the legal parent, that the child as a valid Social Security number and you did NOT check the box that the SSN is not valid for employment.
