According to the user manual:
Use this menu to adjust 3D brightness, the 3D display format and other 3D settings.
Signal > 3D Setup > 3D Format
Use this setting to select the 3D format supported by your video device. In most cases, the
projector will correctly detect the 3D format when this option is set to Auto. You should
only select the 2D, Side by Side, or Top and Bottom formats when your projector
doesn’t properly display 3D images. See your video source documentation for
information on which mode to select.