I have battled with this for so long now I've decided I should just ask the question. Is there any way of making sure that any 12x12 paper you bring over to a new canvas or template etc is dead centre? I currently drag and drop from the area above the ruler but then end up having to make adjustments to get it to be in the centre which isn't always the easiest to do when you don't have great eyesight and its a lighter colored paper. I don't mind it being in the wrong spot in the layers palette as I can easily see it in the layers palette so can shift it around. I am on Windows 10 and use PSE 15 if that makes any difference
If the paper is open in PSE: Hold Shift while dragging the paper onto the canvas. It should "move" right onto the center of your 12x12 canvas. IDK if this works with PSE, but I can drag and drop a paper right from its kit folder onto my canvas; that also centers the paper.