The system does not determine what calendars in a unit to show people. It's completely up to them as to which ones they subscribe to.
That said, the subscription function isn't real obvious. You have to click on the ">>" icon at the top of the divider bar that separates the left side from the calendar display. Only then will you see all the calendars that are available to you.
Have you searched the
Help Center? Try doing a Google search and adding "site:churchofjesuschrist.org/help" to the search criteria.
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Profile to include your general location.