Scroll View Size not match with the device screen in xcode

Ok, I tried the page with several buttons but all of them will not fit in one screen. So, I create the scroll view and the view and then put all of buttons inside the view. The storyboard look fine. Other devices such as iPhone 5 and 5S look fine but when I tried 6 and 6 plus, the size of scroll view was incorrect. I couldn't figure what went wrong.

via Chebli Mohamed