Enter to Changhong CRT TV Service menuDecrease the television volume to 0. Press MUTE button on the remote control. Text “Mute” appears on the
screen. Then press and hold the MUTE button on the remote control and MENU button on the TV pannel at the same time for 3 seconds and the TV enters the S mode.
Press program up and down to select parameter and use volume up and volume down to increase or decrease the data value.
Don't forgot to write down the original data, original data will use for restore the original factory settings if you fail to make your own setting in your television system.
Photo credit : lighthom.com