If you are taking Witchery you can choose your starting spells. It's only if you find random spells that you can't choose them
Ah ok. I was confused too. In the rule book for Abilities is it written "Witchery:
You have been trained by a talented witch. You start knowing the recipes for 3 spells determined at random (pg. 54)."
So, I would have rolled randomly for this ability as well.
Woops, forgot the rules for my own game. Ha. Ah well, do whatever; Random, picked, combination. You are all welcome to make the game into whatever form gives you the most fun.