Hi Iain.
Press the OK or list button and then scroll left/right. You’ll see 8 separate lists, the first three (TV, HDTV, Radio) are pre-loaded as soon as you run an autotune. These cannot be custom sorted.
The remaining 5 are favourite lists, where you can add whatever channels you like and in whichever order. You can also rename the lists themselves, eg. to make separate lists for different people in your family, or types of channels (news, shopping, +1 etc).
Hope that helps.