How do I set the timer on the Homedics UHE-CMTF91?

Press the timer button to cycle through the available auto-shutoff settings: 4 hours, 8 hours, 12 hours, and 0 hours. To cancel the timer at any time, press the timer button until 0 hours is displayed. Always ensure the humidifier has a full tank of water before using the timer setting. (Page 7)