Found the manual online: http://www.echowell.com.tw/images/pr...red_set_en.pdf

Looks like almost everything is set with one button. Switch to odometer mode and hold the button to set your tire size. Press the button to modify the digit, hold for two seconds to change the flashing digit, hold for four seconds when done. Same with clock, except you're starting from clock mode. Do an all-clear with the button on the back if you want to reset the current odometer reading or switch between mph and kph.