schpeelah: You want the "Use only the power from the current band" order from the Orders menu.
tinyE: But I don't want to use the Orders. I just want to cast a power.
Someone told me that early one you really don't have that option; it just uses all the powers as is allowed at that time.
Well, am gleefully replaying it (again again, what can I say, I love that game - for what it is and for what it could have been), and I confirm : you can't play without the orders. The orders define whether you mean "use this power" or "use all powers up to this power". Or even "use powers only when a human is nearby". Or even "use powers only when this specific human is nearby". And stuff like that, more refined and more combinable as you go.
But the basic one (unlocked by default) is "use this specific power only". If you don't tick it, they use all the powers below it aswell.
So, the answer is two posts above. Now give him his "solutions" rep points, before I unleash a headless horseman on your ass !