Forgetting who's in charge

I don't know where we stumbled along the way giving power over to my kids. Whenever I tell them they must do something, like not turn on the computer, but pick up a book instead, I'm shocked how little resistance I get. I tried this on my soon-to-be nine year old, and after a couple of "I'm so bored", she picked up a book in a huff, and then continued to read it for the next several hours. I finally told her it was lights out and she had to put it down. Wow, we have so little power over them, and it's so easy to forget.