Changing Resolution in game messes up UI and Mouse Input

Starting in 1920x1080 the game looks like this

http://imgur.com/PcUIdwb

however once I switch to 1280x720 it looks like this

http://imgur.com/0nvX3Yy

What's causing the UI To do this? Should the canvas be stretching like this? Also I need to hover the mouse several pixels above the buttons to click them after I switch to 1280.

Code looks like this

   public void ResolutionOnePressed()
     {
         Screen.SetResolution(1280,720,true);
         PlayerPrefs.SetInt("Resolution", 1);
     }