macuser_22 has shown you exactly how to enter the self-employed health insurance deduction the "right" way (i.e. no override needed).
But note that TurboTax may have to limit or eliminate this deduction based on your Schedule C income and/or your self-employed SEP, SIMPLE, and qualified plan deduction.
Is your issue that you entered the health insurance deduction in the interview but nothing appeared on line 16 on Schedule 1 (1040)?
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