Business Unit privacy with other business unit

I am using Microsoft Dynamics CRM 2016 on premises version.

I have made two business units TXP_1 and TXP_2 & added 3 security roles with in each of the business unit.

the Parent of these two business units is AXP.

There are two problems,

First is that when i log in from the user that belongs from the TXP1 or TXP2 it shows AXP beneath the user name on the UI. 

& and Second problem is that, there is no privacy between the users of both the business units.

Please help. :(