Answer

Flick the “joystick down” to enable crosshair or switch different color or type of crosshair. (PS: Screen Assistance in OSD menu only showed the default color or type of crosshair that you want )

Models

Optix MAG271CR, Optix MAG271CQR, Optix MAG27CQ, Optix MAG24C, Optix MPG27CQ, Optix MAG271C, Optix MAG241C, Optix MAG27C, Optix MPG27C, Optix MAG241CR