I am new to Music creator 7.  I upgraded from Creator 3.  I am trying to listen to the tracks through headphones.  I have disconnected my speakers.  when I load a song, I get the message "Silent Buses Detected" because it doesn't see the speakers.  I cannot find where to change the output for the tracks.
Can anyone point me in the right direction?
 
Thanks in advance.

In EDIT->preferences->Devices the check boxes select the audio devices that are available.  These are determined when MC starts up, so if your interface is unplugged when you start MC it will probably not show up here.  On my laptop, I have an option for headphones and another for the laptop speakers. 
 
You should be sending the audio output from your tracks to a master bus (but being new you may not have figured that out yet).  The output of your master bus then has its output sent to the headphones or the speakers.  This is selected from the output drop-down box near the bottom of the master bus when displayed in the inspector view.

If your tracks are individually set to your output device, then each of them will need to be changed from headphones to speakers or what ever is appropriate here.

Welcome to the forum.
If you're using the computer sound card, you need to enable the headphone output in the sound card's properties. It should then appear in MC's list of available outs to use.
Or are you using an external audio interface?