Please how can I change my birthdate because I mistakenly sent a wrong one to Yahoo?

I mis-entered my birthdate not knowing quite alright and sent it to Yahoo.It was during a certain registration that I entered my real birthdate and it said that it didn't match with the one I gave to Yahoo.My real birthdate is 11 March 1985 but I don't know what I mistakenly submitted to Yahoo the 1st time I registered.Please help me.