There a few reasons why the information could be incorrect:
The time on the display is set incorrectly
If the time or date has been set incorrectly the display will show information using the wrong time or date. This can be fixed by changing the display time or entering the correct NTP server.
Subject and/or details are not showing
If all information is presented on the display but the subject and details are not showing or incorrect then it's that the settings on the room in Exchange need to be configured. This can be done by performing the following command on the room (using PowerShell or the GUI):
Set-CalendarProcessing -Identity firstname.lastname@example.org -AutomateProcessing AutoAccept -DeleteSubject $False -DeleteComments $False -AddOrganizerToSubject $False -RemovePrivateProperty $False
This should be done for each room.
The display is linked to the wrong room
When configuring the display a specific room is required. It's possible to link any room to a specific display, so it's good practice to check if the display shows the correct room details when activating.