When was the last time you signed into this account from the Yahoo website? Yahoo deactivates accounts that haven't been signed into at least once in the last 12 months. Once the account has been deactivated it's unlikely you can recover it.
Reasons Yahoo deactivates or deletes an account - https://help.yahoo.com/kb/SLN3057.html?impressions=true
If it's been years since you last signed into this account then what happened is Yahoo deleted your account and then recycled your email address for public use. Someone else claimed the email address and they set their own recovery options. In this case you're trying to recover an account that is no longer yours.