When browsing boards and reviewing reports as a supervisor you are using your own account. However, when activating Speak Mode, supervisors have the option of launching Speak Mode as themselves, or as one of the communicators they supervise. You can also switch between communicators and their boards at any time.
To activate Speak Mode using the home board of someone you supervise, find their name on your dashboard and hit the dropdown. Then select "Speak Mode" either as "me" or as the communicator. If you select "as me" then any logs that are recorded will be saved to your account. This is better for modeling as it won't record false information to the communicator's log. If you select to speak as the communicator then any button presses will be recorded to the communicator's logs, which would be better if you were physically handing your device to the communicator for them to use.
Once in Speak Mode, supervisors have an additional option in the menu. When you hit the profile icon in the top right corner you will see "Switch Communicators" which can be used to quickly switch between different communicator accounts and their boards.
The current communicator will be highlighted. To switch to a different communicator or their boards, select the communicator from the list. You can decide by toggling the checkboxes whether you want to jump to the selected communicator's home board, and whether to active Speak Mode as the communicator, or as yourself.
You can always who you are currently communicating as, and to whose logs any button presses will be recorded, by looking at the profile icon in the top right corner. If the icon matches your profile, then you are speaking as yourself. If the icon matches the profile icon of one of your communicators, then you are speaking as them and any button presses will be recorded to their logs.