If you have registered multiple organizations, or have been added as an employee to others, they will show up for you in your dashboard pop-out menu and you will be able to navigate between them. The only requirement is that you've added them/been added to them using the same email as your original account.
To navigate between multiple orgs, you will need to open your dashboard pop-out menu and select the dropdown menu
From there you will be able to navigate between different organizations that you have access to!