In Photoshop CC 1.2 I am using the Quick Export as PNG option on an Artboard. My artboard is larger than the image it contains. I would like the image to keep its position relative to the artboard when it is exported. Instead, Photoshop repositions my image to the bottom center of the artboard. I know it can be prevented because the first ten images I exported were perfect. Suddenly, they are all bottom-centered! Help?