The very first time you launch SchoolCal should define the Default Year as the current year of the day you activate the application. From that time forth, no year changes will occur unless you do it here.
The stepper button on the right of the input box will change the date one year (up or down), or you can simply type the new year from the keyboard.
The nature of SchoolCal is to assume a September - June school year, therefore, the Default Year is always in the fall, and the end of the school year is always assumed to be June of the following year. Thus, changing the Default Year will affect all of the Vacation Dates, correctly assigning each year to the proper month. These changes are immediate; they are written to the default database and displayed in the Text Field as well. The only dates that are NOT affected are those already generated on the Other Dates Tab. Therefore, it is best to set the Default Year first, before you do anything else.