If the arrow on the right edge of the display screen is at the top next to prog it is running whatever is stored in the program. If you use the arrows to change the set temperature it will hold that setting for 3 hours or the next time in the program, whichever comes first. If you do not want to use the program press the prog/man button to switch to the manual mode. The arrow will move to the bottom of the screen. It will ignore all programming and stay on the temperature you set with the arrows.