How can I show/hide when a message has been read?

By default, admins/managers/supervisors can see when a message is read.
Example, this message was read by Mark on Oct 25.

Employees by default can not, their message will look like this

To toggle this ON/OFF,

1. Go to MANAGE MY BUSINESS
2. Go to MANAGE SECURITY GROUPS
3. Find SHOW WHEN A MESSAGE HAS BEEN READ and toggle it on/off