Comcast Digital Cable TV Box Hint: 

Does your TV volume change significantly when switching from your Cable Box to a VCR or DVD?  Is the volume level on your TV too low all of the time?

You can fix TV volume issues by pressing the "Menu" button on your remote ONCE, then AGAIN (two times, total). 
A drop down menu will appear.
Scroll down to "VOLUME" and using the left and right remote shuttle buttons, select "FIXED" rather than "VARIABLE". 
Exit all menus and your TV volume should remain the same through the cable box as it is through other sources.

If this does not solve your volume problem, call ComCast at 239 432-9277 or www.comcast.com/support