As a homeowner, you should reset the opener to prevent outsiders from opening the door with a remote that's set to a Liftmaster default code. A simple procedure allows you to reset the opener for one or more remotes.
doorsill - the sill of a door; a horizontal piece of wood or stone that forms the bottom of a doorway and offers support when passing through a doorway. doorstep, threshold. 1  doorway, room access, door, threshold - the entrance (the space in a wall) through which you enter or leave a room or building; the space that a door can close; he stuck his head in the doorway.
Sills are part of the window trim, which also includes the head casing, side jambs and the apron, the piece attached to the wall beneath the sill. Each plays a part in keeping the window structurally sound and the elements out. Window Trim Ideas and Styles.