Selecting the "Private" category for one of your meetings in the Outlook calendar does not automatically hide the title in the FM portal or on the info displays. If you want to hide the title there as well, follow these instructions.
Procedure in Outlook
When creating a meeting in the add-in, select the "Confidential Meeting" checkbox.
The meeting title will be replaced by a default text in the FM Portal and, consequently, on the info displays.