By default, calendars in Exchange Online will only show the free/busy status with no details about the appointment when viewing other users’ calendars. If you want to know how modify this then look no further.
Read more “Managing calendar permissions in Exchange Online”Show meeting subject in meeting room calendar
By default Office 365 will only show free/busy when users are viewing a meeting room calendar. You can alter this to show the subject instead by running a few simple PowerShell commands.