thx for your answer. i´ve done a lot of testing and was wondering, why my cloud representation was so unreal. there weren´t enough cloud-parts. just one picture. no volume.
now i found out, that the testing of the "Rendering Options" from the .org forum messed up my rendering settings, even though i had unistalled it and re-downloaded xplane 11.
After a clean Installation it all works fine, and i´m happy with your standard configuration (i also like the other settings). Although some clouds are turning. But now i have much more parts in one cloud- so the effect is not so strong.
as always: the user is the main problem
thx for your help