It's simple enough, when you simulate the AI takes over captaincy. If you don't simulate (or stop between each over) you can pick which bowler bowls each over.I dont think its good when you become captain of your side and you cant pick bowlers and how they are automatically selected for you, thats the one fault i still have in the game
Though there's a bug that I still don't think is fixed (I'm not captain in my current career) that means if you move yourself in the batting order it gives captaincy to the player put in your position in the batting line up in the next innings.