If you use both Control Center and MyLevel3, you can select which portal you use for each enterprise ID you have access to for your organization.
Control Center lists the enterprise IDs your user profile is currently assigned to and the default portal for that enterprise ID. If you already have a default enterprise ID selected, Control Center lists it in the My Default Enterprise section. (You'll also see a My Default button next to that enterprise ID in the My Assigned Enterprises section.) In the example shown below, there is no default enterprise ID.