Distribute Roles
The only role that can be taken on by users themselves is that of Scientist. According to the default settings, further roles can only be assigned by the administration and the PA, whereby the role of admin can only be assigned by an administrator. This can be done in various ways. Firstly, you can view and edit a list of users and their roles via the Distribute roles button at the top left of the Roles & Rights page. Secondly, you can go to the user's profile page, select Edit profile and adjust the role under Account.

Assigning roles in the user profile under the tab Account
The assignment of roles is also regulated in the rights. You can assign roles the right Assign user roles (except admin) and allow other roles to assign Admin rights.