Once you have logged into Dex you can click on the profile icon to switch accounts and access your other organizations.
Click Switch Login Account.
Click on the Organization that you would like to switch accounts to.
Merchant organizations will have a M next to it and will begin with a 3 series 6 digit number.
Partner organizations will have a R next to a 2 series 6 digit number.
You will see the organization that you switched to on the top left side of Dex.
If you need to switch to a different organization you can repeat the steps provided.