I hit the wrong button and now can't get it back to mph. Tried what they said several times "hold the set button down for 3 seconds then press the up arrow."But it don't change. Also have trouble scrolling it keeps showing RPM C on the other side of display. Every once in a while I get Km-M tried pressing buttons then but nada. Pretty sure its me but don't know how to correct it. Hoping for help!