User rights are sooo confusing / #6065

Hello out there,
i just installed the streber for the first time and I do love it right away. I also tested a lot of other systems but this seems to be the best (for me).
But (there is always a but) I can not understand the userrights system at all.
I have one project which has two members of a team. One is me (admin) the other one is "Alex". Alex is defined as a "Client". If Alex logs in he should only be able to edit those tasks that are assinged to him and/or owned by him and/or client-edit. But he can also edit tasks that are set to higher status ? Furthermore he should only see those tasks that have a pub-stat less then open. But he sees also open. I found that user table in this wiki but it says something different.
Or do I understand something completely wrong?