how can i see date of my birthday in account info?

Answer 1

You cannot : That info is buried in the Yahoo! archives, and will only be accessed by them, if and when you lose, or forget, your password :
When applying for your new password, you will be asked for your birth date - and unless it coincides with the one you had initially entered, you will be refused the new password, and denied access to your Yahoo! e-mail box !

Answer 2

if he mansion the u can see....
Go to Profile