currently, as confirmed by Microsoft support, when user logs into office 365 on the customer side, they after choosing the dynamics 365 business central icon, are then presented with two main options, production and sandbox. However, the sandbox one is based on the default created sandbox, regardless of how many other sandboxes are created. Additionally user cannot change the selection of that sandbox, or know which sandbox they are in. Thus, it would be nice to have more tiles appear for more sandboxes, and have each sandbox appropriately named with the actual sandbox name.
Category: General
Ideas Administrator

Good news! 
As of update 16.1, you will see one Business Central tile per environment type, that is, a tile leading to your production environments and a tile leading to your sandbox environments, irrespective of what your environments are named or how many you have. If you have more than one environment of each type, you will be prompted to choose which environment to navigate to. We believe this makes it possible to consistently switch between any environment, which is the primary suggestion in this Idea. We will not have a tile per environment, as this can result in too many tiles being displayed and is not in line with other Microsoft apps.

Learn more about the new Sandbox environment switcher.

Best regards,
Mike Borg Cardona
Program Manager at Microsoft