From OFF > Press Middle Button Once > Time Mode
see Page 48 of the User Manual
In Time Mode
Press Right Button until Settings is shown (My Hint: one press at a time)
Press Middle Button > Cycling Set is displayed
Press Right Button until General Set is Displayed (again, one press at a time)
Press Middle Button until Units kg / cm or ft /ib is displayed
Use Right Button to toggle between the two
Press Middle Button to accept the units
This "should" convert all your units to / from metric and imperial