Business units offer a way to separate users that operate in different areas of your business. Live Assist for 365 is compatible with users who belong to different business units.
Business units can be changed as follows in Dynamics 365:
From the top menu, select Settings -> Security
Then select Users:
On the next screen select the user you would like to change business units for and select Change Business Unit
Finally select the business unit you would like to move the user to and click OK.
If you change the business unit a user belongs to, Dynamics removes all roles which were assigned to that user in their previous business unit. Live Assist for 365 automatically adds the Live Assist roles to the user in the new business unit no more than sixty seconds after the user’s business unit was changed.