[. . . ] All Information in this manual may change from time to time without prior notice. [. . . ] Be carefully to your LCD monitor, it's very exquisite but easy to broken. Audio InThis can be connected to the PC audio-out connector of sound resource. There are 5 keys for user to set up the monitor, including "Auto Adjust", "OSD menu", "Power", "Adjust <->", "Adjust <+>". Menu (Function) M Function Select Button: This button allows you to select the control functions down in the OSD. When the power is on, the light is showing green, Stand by will be orange. Adjust your Speaker Volume via your PC computer Speaker Volume control icon. [. . . ] Check: Make sure the resolution or refresh rate match with the Display Mode. [. . . ]