They need the birthdate because that information is not shown to anyone, even a hacker. They have it stored in their own database for purposes such as this. You should really use a legitimate birthdate in order to regain access. Problem is that you do not remember it now. Look at it this way. Any person can pull up your account through hacking and look into your email and write down all accessible info such as folders, emails, personal info. But since the birthdate is not shown, only the REAL account holder can verify this information. If you do not know the birthdate, then how do they know YOU are the real account holder? I'm not defending Yahoo as they do have their issues but you just have to look at it from both sides. If someone in your place asks for the new password and they give it to them, Yahoo is now responsible for giving away info sensitive to your account. You would be quite upset at them wouldn't you? This is why they ask for the info that is needed and only known by Yahoo and the account holder.

My advise cannot help since you do not remember the birthdate you entered, UNLESS you happen to remember it. Other than that I have a feeling that you won't regain access.

Also, I have not known of any updates to Yahoo except downloading a new version of Messenger. If you clicked any links in email to get a "new update to yahoo" then chances are that you clicked a link that was not valid, therefore you were phished. It happened to me through a photos link but I gave them the birthdate as well as an intimate description of the account.

Good luck to you. Its no easy task I know since it happened twice to me since i opened my account in 1997.