Hello sue1491,
Thanks for using the Apple Support Communities. We understand that you're being required to get approval for items purchased through iTunes and App Store with the "Ask to Buy" feature of Family Sharing. Looking over article, Approve what kids buy with Ask to Buy, this feature should only be available to family members under the age of 18. Given this, you might want to double check the date of birth you have listed for your Apple ID account.
If you need to update the date of birth to ensure its correct on your Apple ID account, follow the actions provided here: Update the birth date associated with your Apple ID.
Should the date of birth be correct in the system already, your best option would be to reach out to Apple Support so they can take a closer look into this issue with you.
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Best regards.