Hello, I just downloaded and began playing Trivia Crack. But I have a questions about using Power Ups. Every once in a while, a screen appears that lists the power ups at the bottom of the screen and shows a close button. How do I select a Power Up to use? The only button that seems to work on the screen is the close button, so I don't know if I'm getting another Power Up or not. Also, how can I take advantage of a power up if I don't know an answer?