Setup Question

You likely have more than a single HDMI port. Even my 4 year old cheap Visio has 3. I use one for the DVR and the second for the BluRay player. Your sound system might be connected to the DVR, for example. I have my ATV on the 3rd HDMI input. Cycle through the menu for your TV's inputs or better yet, crawl around the back.
YMMV

 

You can always buy a HDMI switch from monoprice too.

 

a switch is only necessary if you have an inadequate number of ports. when you say 6 inputs i assume you mean total, of the 6 how many are hdmi?

 

yellow/red/white = composite video (yellow) and stereo audio (red/white)
those really won't help you with the aTV.

you mention "bose sound box" there is a chance that has multiple HDMI ports on it.
you would then use the bose box to change what you're watching on the TV.

so both the satellite box and the aTV would wire to the inputs on the bose, and the output of the bose would go to the TV.

if it doesn't you will need an HDMI switch check here for the listing at monoprice.
also look at monoprice for your HDMI cables. you'll get them for much much cheaper than you would at best buy, and the quality will be the same.

or depending on your TV, it sounds like it may not be full HD (possibly an older ED TV).
in that case you could use composite video for your satellite box, and probably not see too much loss in video quality.

 

Actually...is your satellite box HD? If not, move it to composite and plug the ATV into the hdmi.