How do you change the party leader in final fantasy 13?

im playing as hope and vanilles part right now. some how i change dthe leader to vanilla. it sais to go to main menu-paradgims- battle somthing but when i go to the main menu nothing sais paradgims. theres status, abilities, equipment, invetory, map, datalog, and settings. no paradgims. the book guide that came with it sais press lb to do paragims but thats just like a shroud thing??? please help|||You can't change your party early in the game, and the paradigm menu won't show up yet, either. As you progress through the story, there will come a time when you have quite a few members in your party, and eventually it will let you pick your battle team out of these members. I don't need to spoil when, because you'll know when it happens. You'll find it in the exact place you just mentioned. Just keep playing, and eventually the world and its possibilities will open up to you.^^|||It does it auto for now. You did just start. You can do it later.