Favorite channels are used with the option "Next / Previous use favorite channels only". Once this option is turned on, you can use channel up or channel down buttons to switch to the next / previous favorite channels.
To show only a certain number of channels in the guide, depending on your intention, you can do one of the following two things:
1. Hide all other channels. Only channels that are not hidden will appear in the guide.
2. If option 1 is not what you want, (i.e. you still want some channels occasionally available, even though not often), you can sort channels. Put channels that you want most to the top of the list. This way, those channels will appear at the top of the guide, other less used channels appear lower.