Why did ICloud not update my new Apple user ID when I changed it on my Ipad

I updated my apple account with my new email address and changed my apple ID which went fine. My Ipad is working fine. But my Iphone 4 will not let me use ICloud as it is still looking for my old user ID and email address. I can't edit that on my IPhone 4. I went to the apple site and logged in here and everything is good. What can I do to correct this issue?