I had the same problem and have been waiting for someone to answer but I've just found my manual.
1.Select the overview menu - Press and hold the menu button until the overview screen appears.
2. Select installation menu - Press the menu button once more and the installation menu will appear.
3. Select frequency - Press the up and down arrows to highlight frequency. Press and hold the + or - buttons until your TV starts to tune to the next available station.
4. Number the channel.
5. Store the channel.
Hope this helps because it was driving me mad!
Jo
October 2005