So I could answer this myself as well.
I had “Initially… checked” by 2 of 4 different newsletter but this is not for the registration process. In the subscription profile page configuration I can select “Forced preferneces” which newsletter is used for the member registration.
Now I’m coming to the point…..:
I like to have different newsletters for wp member registration and for non members. How is this possible to manage this?
The additional newsletters for members is marked as “private”.