Most JVC car stereos have an AV menu where the time on the radio can be changed; the AV menu button can be pressed and the time can be adjusted using the up and down arrows. The radio can switch between hours, minutes and time of day by simply pressing the enter button.
Along with the car, the stereo needs to be turned on to adjust it. After the stereo has been turned on by pressing the power button, the AV menu button can be pressed. Depending on the specific model of the stereo, the AV menu button may be in different places, although it is usually toward the top of the stereo. The menu can be scrolled through by using the up and down arrows. Once the clock is shown on the menu, it can be accessed and adjusted by simply pressing the enter button. Once the hour, minute and time of day have been set, the enter button can be pressed again to go back to the regular stereo. If the time is still not correct, the menu can be accessed and the clock can be adjusted to get the correct time put into the stereo.