Just press the button in the display while the engine is running. It will switch to trip A then trip B. Hold the button down to reset. You can view it while the engine is off too, but I've never had a needto do it.This is my first posting. I bought a 2010 forester about a month ago and I cant figure out how to use the trip computer. The time and the temperature are visible at all times, but no matter what I do I cant get the milage numbers to show up. I tried following the manual, i pressed the + button while the engine was off, the the numbers flashed where they need to be and thats it (I do not know if i turned it on or off). Can anyone give me some guidence?