Go from Scene to viewcontroller

I have a simple game. there are two Viewcontroller. after pressing "play" on the first viewcontroller i have performed a segue to the secondviewcontroller. this secondviewcontroller contains a GADBannerView and a button to stop the game and presents a Gamescene. if the user loses it shows up a new game scene. if the user clicks on the GameoverScene the game restarts. I would like to to perform a segue after the user press on the button and i would like to go back to the first Viewcontroller. I've made it in the storyboard. the problem is that the game doesn't stop. (i know it because i have a background music) and once i'm in the first viewcontroller if I click again "play" the game doesn't work as it should. i've figured that the problem occurs when i click the "back button". how can I dismiss the game scene and go back to the first viewcontroller?