Turbo tax is saying I don't qualify for the child tax credit because my child is 18 they did not turn 18 until January 2025 how do I get this corrected in turbo tax

For the Child Tax Credit on a 2024 tax return the child must be under the age of 17 on 12/31/2024.  If the child is age 17 or older then they are only eligible for the Other Dependent credit of $500

You lose the child tax credit when the child turns 17.   If the child was older than 16 at the end of 2024, you get the $500 credit for other dependents instead.

https://www.irs.gov/help/ita/does-my-childdependent-qualify-for-the-child-tax-credit-or-the-credit-for-other-dependents