The phrase "to change the date" means to alter or adjust a previously scheduled event by moving it to another day. This can be done for various reasons, such as conflicts with other commitments, unavailability of venue or participants on the original date, or simply because the organizer wants to choose a more convenient time for everyone involved. The new date chosen may be earlier or later than the original one and it is usually communicated to all concerned parties so that they can make necessary adjustments in their schedules.