How Do I Change My Name without losing my credits under current name?

How Do I Change My Name without losing my credits under current name?  My IMDb name is Dave, but I go by Dave or David.  All my acting materials say Dave, but I sign contracts with David J. (last name).  Several times the movie credits say David and it doesn't show up in my IMDb credits until I contact them and they change it to Dave.  I'm now thinking of changing my IMDb and acting name to David to make it easier.  How do I do this without losing current credits and having to recontact people to change the name on the movie credits?