In the rules it says both that the first 4 scenarios are related, and that each one is about a different group of survivors. With out spoiling, can anyone tell me if my character from scenario 1 will really not be there for 2? Should I tell my fellow players they are picking their charecter for 4 games or 1?

Each game, you pick new survivors. This could potentially mean the same character will pop up, but it's not likely, especially being controlled by the same person. What I find most interesting is that with multiple players, you pick your character blind, meaning you don't get to see what the others are picking. Each person is dealt two characters facedown and you don't reveal who you picked until everyone has finalized their choice. Obviously you can ignore this rule if you really want, but I kind of like it.

11 hours ago, mwmcintyre said:

... , but I kind of like it.

In a "campaign"? I suppose in a campaign you "should" prefer to remain "yourself" instead of having "different personalities" ?

But it's not a campaign in the traditional sense, you're not meant to play the same character. It's a series of stories/scenarios that are connected, much like an anthology of short stories or an anthology tv show. Episodes are separate and self-contained, but they have a connecting thread running through them. I wasn't expressing a preference one way or the other on that, I was just saying I like the fact that you can't game the system by designing a team if you play using their setup rules(playing solo being an obvious exception). It's a fun thematic bit, you're strangers who wake up in the same place not having any prior knowledge of each other.