How can i change the gestures needed when voice over is on?

On the IPhone 5 I've turned on the Voice Over setting, so my nephew who has CP and is physically challenged can hear the posts in fb and texts. The problem he's having is with doing the double tap fast enough and using three fingers to scroll. He doesn't have the fine motor dexterity to make it work and he is getting very frustrated. He was so excited to finally hear the texts instead of someone reading them to him. I tried to set the physical motor setting, but it didn't work for fb. Any suggestions or experience with this issue you would kindly share would be greatly appreciated. Thank You.