how to change child tax credit information for my return to be accepted

If you entered your child's information correctly in MY INFO you will automatically get the $500 credit for other dependents for a child older than 16.  Check the information you entered for him.

Make sure you have entered your child as a dependent in My Info, and that you have entered the child's Social Security number.    Careful— do not say that your child’s SSN is not valid for employment.  If your child was born in 2024 make sure you said he lived with you the whole year.  There is an oddly worded question that asks if the child paid over half their own support.  Say NO to that question.