How do I make my fruit leather soft?
You want it to form a thicker layer on the sheet, and you don't want to overdry it. The toughness is from drying a thin thin layer for too long. Cooking the fruit a little can help with that. So can fiddling with what fruits you use.

Thing is, though, it's not going to be like the stuff you buy. Read the ingredients: most have added sugar and some sort of thickeners like gelatin or xanthan gum.  

For me, what matters is the taste. As long as it doesn't shatter when I try to eat it, I will accept a wide range of textures. I choose the fruit for flavour and availability and go for the simplest possible preparation, which is pureeing raw fruit.