On Xcode 6.1.1, running Swift in Main Storyboard:
For some reason, whenever I create a UILabel or UITextField or any element within a View Controller, if I try to resize the element, it only stretches towards the RIGHT or DOWN. If I stretch to the Left or Up, the entire View Controller moves on my storyboard. I've been told that there may exist a preference setting that I can tick/untick to solve this problem, but I have not found it.
I think your command key (⌘) is stuck down. The behavior you're describing happens when you command-drag on the left or top of an element.