Several improvements
There are a few things you could do that would improve this. Number one, the layout is a Big deal. You should have some sort of stop sound button. Either on the soundboard itself or have Spacebar stop all sound (Make sure you write it somewhere on your board if you do). Usually soundboards have a certain person they're taking sounds from. If you look you'll notice there's a slew of Arnold, Jim Carey, and Simpsons boards. Find you're own person and try to get the clearest sounding files for your board. These ones sound like they're recorded from a crappy mic.