I have realised that, in the case of pillows and iPhone cases, the image' layer has to be dragged to the left a little bit so that the right side's width will look a bit bigger. However, in the case of t-shirts, I have to drag the layer to the right side a little bit so that the image can stay centred. Well, all this seems to work for me, I hope they come out well when purchased. Awesome work by the way!

True. I really think new products shouldn't be "auto-created" from previous posts. Feels like I'm losing control over my work. And thanks btw!