"Event Groups' is the default event group for all users" means that the Authorization Profile is missing a Role with adequate permissions.
As the admin user, edit the associated Role and confirm that all desired Event permissions have been granted.
Also confirm that the Authorization Profile is associated with the desired User Group(s).
While in the Authorization Profile, click on the Objects tab -> Presentation Server -> Event Groups -> click on the Source -> confirm that objects have been added (3 dots -> Edit -> add as needed)
Login as the other account to confirm.