It is currently not possible to give only one user the main DoudouLinux menu, the one you get once the system has just finished to start, as his/her own session, while the other users would have another session. The reason is that this menu is a standard GDM menu, which means the activities displayed are indeed fake users with different profiles. Each profile determines the kind of session (either a single application or an LXDE-derived session) and the settings of applications in this session. We are looking at removing this trick in favor of a real activities menu application, but this requires we change the way application settings are handled in profiles.
What you can easily do is to associate one user with one DoudouLinux session, say the PySycache session or the Whole DoudouLinux session. Just click the session menu before logging in from the authentication screen. DoudouLinux is not designed to be multiuser because our design model is gaming consoles. However we know that this can be problematic when the computer is shared between several children but haven’t enough work force to solve this issue in a short time.