Date format on user profile form shown incorrectly - how to change
Date entry format is configurable, what you did was changing the way the date will display on content but not on create content form. To change it go to your field configuration page on content type then find more settings and values collapsed fieldset and inside it look for date entry options and change to whatever.

https://docs.google.com/a/srijan.in/file/d/0B9FG53CLjf-YdEFfdzVEV1hmcWc/edit?usp=drivesdk