12-hour clock on calendar view

Hi all!

on the activities section, Calendar view all of the users can see  24-hour clock (military view) we do not need these on the calendar. Every user has US time zone and date and time format set up but on the calendar we still see this 14..15... - 24-hour clock.

Where is the place in the system I can change this to 12-hour clock that is regular for US?

Thanks!