i'm member of a belgian team called "vlaamse leeuwen" i even regisitered the team myself on several projects.
but i appear in my old teams list "boinc.be", that is when i look at team stats. but when i look for team stats for each project seperatly i apper in the correct team.
how to solve this?

You are a member of BOINC.BE on LHC@home and according to this message, I guess that this team has a higher hash than "vlaamse leeuwen".

Because LHC@home does not export stats at the moment, changing the team there won't affect BOINCstats.

so because of 1 project, i apper in the boinc.be stats?

Yes.
For multi project users with different team affiliations some automated solution has to be implemented, something that's fast and DB-friendly. Obviously this leads to some strange things in the stats for a few users, like you.
If it's not much to do for reprogramming this routine, Willy will perhaps do it. If it will take a lor of thought and could lead to other DB-hickups, he should not touch it.

Be patient, the moment LHC will export their stats, BOINCstats will pick up the xml and with the next update your teamname will be corrected to the right value.