Hi @Marie-Helene,
I have consulted with one of the developers of OJS who had indicated that what you’re seeing is an accommodation that was made for small scale journals.
It was designed so when there is only one person available in a journal for a manager or assistant (copyeditor, proofreader, etc) role, that user is automatically assigned to new submissions when they come in.
The moment you assign a second person in the Editorial Board Member role within the journal, this will stop auto-assigning them to a new submission.
Kind Regards,
Patricia M.
Public Knowledge Project