One or more projection apparatuses, control methods for one or more projection apparatuses, and storage mediums for use therewith are provided herein. At least one projection apparatus includes: a projection unit including an optical unit, the projection unit being configured to project a projection image including a predetermined display item onto a projection surface; a sensor configured to sense a predetermined area corresponding to the predetermined display item on the projection surface; and a control unit configured to: (i) perform predetermined processing relating to the projection image in response to the sensor detecting a predetermined instruction in the predetermined area, and (ii) stop sensing performed by the sensor in a case where a state of the optical system of the projection unit changes while the projection image including the predetermined display item is being projected.