Remove automatic affectation on sub-project creation

Hello,

As "manager" user, when creating a sub-project of an existing project, I always get a new affectation created for myself. This results in many affectations in cases where I have a large project tree structure (many sub-projects, and many sub-levels).
I have checked that the global parameter seems ok (see attached).

Is it possible to prevent automatic creation of new affectation , if I am already affected to the parent project ?
 

Oh, did I miss that option ?
It's not "auto allocate manager to the project" , in Activity tab ?