Method for controlling display system, and projector

A method for controlling a display system including:

• a projector that displays a first image according to a video signal outputted from an output apparatus on a projection surface and includes an operation accepting section that accepts a user's operation;
• and an external apparatus including a display section and coupled to the projector,
• wherein the projector stores at least setting information representing a setting on display of the first image,
• the projector operates in one of a first mode in which a first screen that allows the user to view or update the setting information is displayed on the projection surface in accordance with the setting information and the setting information is updated in accordance with first operation performed on the operation accepting section and a second mode in which the setting information is updated in accordance with an update instruction received from the external apparatus,
• in the second mode, the projector transmits the setting information to the external apparatus, and when second operation is performed on the operation accepting section, the projector transmits operation information representing the second operation to the external apparatus, and
• the external apparatus displays, in accordance with the setting information received from the projector, a second screen that allows the user to view or update the setting, generates the update instruction in accordance with the second operation indicated by the operation information received from the projector, and transmits the update instruction to the projector.