When i play Sandbox mode and pick someone i always get Charlotte de Berry as Captain and never the guy that i actually picked for the starting boni whats up with that tested this with the german version of the game but i remember the oldschool version from the cd back then didnt had this problem.

Isn't the captain you pick your alter ego?
IIRC your alter ego doesn't walk around the island and can't crew a ship so you'd need a another captain for that

It has been a while that I played T2 the last time, but IIRC it's tied to difficulty level you pick in sandbox, which captain you get in game at start. Not long after release of T2 someone wrote a mod randomzing things, but I don't think this is still available somwhere. However, I found a link to a topic explaining how you can change the starting captain quite easily:

http://www.the-nextlevel.com/tropico/cafe/index.php?topic=7081.0