you've gotta make sure the selector switch/button on the turn signal is displaying the temp in your mileage window, then press the right side trip reset. this will also change the time from a 12 hour to a 24 hour clock. read the tips post at the top of this forum page, there is tons of good info there.
<img src='http://www.bmw-forums.com/forum/uploads/post-4-1081744190.jpg' border='0' alt='user posted image' />
<span style='color:gray'><span style='font-family:Arial'>2000 323Ci alpine white</span></span>