In the Results tab you can select the current user from the current user pull down field. You can change the type of the current user by using the user type pull down.
It is possible to add new users by using the Add User button on the toolbar. This will open a dialog prompting you to type a user name and select an age. You can only add users which do not currently exist already.
You can delete users using the Remove User button on the toolbar. This will remove the user and all results associated with that user. If the user removed is currently the active user, another user will be selected as the active user.