I can switch source on my samsung with the tv remote or my cable remote. On the TV remote I use the source button, on the cable remote I use the input button. Either remote will bring up the source list and multiple presses of the button will cycle thru the list.
On mine, both the AV and component are greyed out. I believe it is because I have nothing attached to those sources I think the AV is the same as composite.
Do you have it hooked up for composite or component?.