By default, the tracker box moves with the reference box. If you move the tracker box by clicking in the area outside the reference box, it no longer follows the reference box. The new position is recorded in the Track X and Track Y channels in the Channel Editor and has precedence over the Shift value when the tracker box appears. If you want the tracker box to follow the reference box, you can delete the new keyframe. You can also use the Reset box to reset the reference and tracker boxes to their default position and size.
To reset the tracker box:
The keyframe for the tracker box is deleted and the tracker box moves to the current position of the reference box.
The tracker box now follows the reference box.
To use the Reset box:
The reference or tracker box is reset to its default position and size.