Changing Subs in Mission Menu
In Mission window select the mission. Then on the sub screen is the sub you have to use cause the arrow keys are in active and the player can pick any sub. Well if you put the mouse cursor on the sub name and press tab, the arrow that was in active turns red. The player can then take the mouse and click on the red arrow that is now active and pick any sub from the list making it player's choice instead of computer choice.