Instead of tapping the +image to add a default 16×20 to the wall you may long hold the +image icon to bring up a scroll wheel of sizes (iOS only.)
However, mastering the spread and pinch gesture will really help you get the most out of the app and it’s very easy once you understand a few important things.
*The tips of your fingers do NOT need to be inside the canvas, or even anywhere near the canvas. The spread and pinch gesture is actually allowed anywhere on screen – you can move your hand far to the right or left and try it..
*You can reset your fingers if they get too close together or too far apart, so you can essentially pause the spread/pinch by stopping, and resetting your fingers and then resuming. This concept is hard to explain so I did a periscope video a while back (excuse the low fi quality!) that people told me was very helpful. If done right, the spread/pinch gesture is incredibly easy and really really fast!