Apple TV/FM Radio System - Manual (Page 94)

3 Select a channel from the channel list, then click Edit Name.
Or, you can double-click the channel number or name.
The Edit Name dialog box appears, with any name already
assigned to the channel selected. (Initially, channels have no
names assigned to them.)
4 Type a name for the channel.
To remove a name from the channel, press the Delete key
while the entire name is highlighted.
5 Click OK.
The name you typed appears to the right of the channel
number in the channel list.
87 Customizing the TV Tuner Settings