The Casio 4305 is a watch with analogue display, time zone setting and automatic calibration. This means, the majority of the time, you won't have to set it. There are occasions, however, when the automatic calibration doesn't work, and you may have to manually set the time.
Press and hold the "B" button. This is the lower button on the right-hand side of the 4305. The top button on the right-hand side is the "A" button. Release the "B" button when the watch's display shows the current time zone setting. This number is the difference between your time zone and GMT (Greenwich Mean Time). Before you set the time, you have to specify your time zone.
Press "A" until your time zone is shown on the display. For example, if you're in New York, set it to "-5."
Press the "B" button ten times to exit "Settings" mode. The menu is a cycle, which you move through by pressing "B." Ten presses from the "Home Time Zone" screen should bring you back around to the standard "Timekeeping" mode. The 4305 actually receives a calibration signal and automatically adjusts the time accordingly, so theoretically, after you set your time zone, the correct time should display. There are transmitters in Fort Collins (Colorado), Rugby (England), Mainflingen (Germany) and Fukushima (Japan).
Press and hold "B" again if this doesn't correct the time. You need to go back into settings mode to change the time manually. When you enter "Settings" mode, the time will stop advancing, and the second hand will go up to 12 o'clock. Press "B" three more times to move to the "Hour" setting. Pressing or holding the "A" button advances the hour hand in a clockwise direction.
Press "B" again when you have correctly set the hour hand. This moves you onto the "Minutes" setting. Change the minute hand by pressing or holding the "A" button, just as you did for the hour hand.
Press "B" again if you want to set the date. From the "Minutes" setting, pressing "B" will take you to the "Year" setting, then "Month" and "Day." These are all changed using the "A" button. Three presses from the "Day" screen will take you back to "Timekeeping" mode. The "Seconds" setting is actually before the "Hour" setting, but changing this is somewhat redundant, as it will automatically start from the 12 o'clock position if you don't alter it. You can just return to "Timekeeping" mode on the minute if the second hand's accuracy is important to you.
Set your 4305 up by the window when you go to bed. The calibration signal is received through the night, so doing this will keep your watch accurate. Make sure the "6" is closest to the window, and that there are no metallic objects or any appliances nearby, as these can affect the signal.