//main timeline in frame called actions or similar
var varClip1:Boolean = false;
var varClip2:Boolean = false;
var varClip3:Boolean = false;

//assuming buttons are called button1 button2 & button3

button1.onPress = function() {
  if (varClip1) clip1.gotoAndPlay("out");
  if (varClip3) clip3.gotoAndPlay("out");
  if (varClip2) clip2.gotoAndPlay("in");
  else clip2.gotoAndPlay("out");
}