Why is there no button to click for Candy Crush Soda Friends.

All of the games you have a choice of all on your friends list or only the people you have that play that game.  I don't always know who plays or not.  Since I can't just click on the people who play and I won't purchase anything, I guess that means that I won't be playing this game.  I need to unlock the next challenge and I don't know everyone who only plays this game.