When you are setting up your default calendar search, there feature that gives you shortcut dates to the calendar fields of; Tomorrow, Until Friday, Next 7 Days, Next Week.
This works in conjunction with the Candidate Availability tab rather than the Availability field in the Candidate Personal Information tab.
If you did want to search the Availability field in the Personal Information tab, you can use the Additional Fields tab in the search pop and select Availability.
If you leave the Calendar Availability date fields blank and the search is run, it will show the current date. If you don’t want this to impact your searches, just make sure that the toggle button is set to AND.