my calendar on my iPhone shows an "Untitled Account" instead of iCloud

My iPhone 6 on the calendar isn't sincing with my other devices and the when you hit the calendar at the bottom of the calendar app it takes me to a page that has

"untitled Account" at the top of the calendars instead of "iCloud " like the rest of my iPads and my wife iPhone. How do I rectify this problem? It all started after I uploaded the new software for the iPhone 6. It seems every time I do this I have nothing but problems. At any rate, How do I get my calendar on my iPhone sinc'd up with everything else???