I have spoken to Support and learned that there is no way to edit what field the Calendar Widget displays.
We have an Intake Form on Monday.com to manage a content calendar. Unfortunately, the Calendar Widget seems to arbitrarily select a field to display. In one test I created, it chose to display the email (the first question in the intake form), Thinking we could “hack” the desired behavior, I then created another Intake form and made the first question be the “Content Title”. In this second attempt, Monday.com created the Task column by default which then became the field that displayed on the calendar.
We can not successfully create a content calendar on Monday.com because of this lack of functionality. This seems like a very simple feature but without it, any social, marketing, events, content, or community team is unable to use the product for their workflows.