Your best bet is to press the "input" or "source" button on the Sony. It will be either on the side, or the back/bottom and you press once to bring up the input, and every push after that will change the input. So two pushes for each input, because you'll want to delay pushing it again until it switches inputs.
on a secondary note, using a 32 series remote, you likely have a 922 DVR, and as such, is this TV1 or TV2? If TV2, change the TVs channel number to 60, 73, 75, or 116. Tv2 is the one without a receiver connected directly to it.