Unfortunately, there's no way to set the input selection. In most cases, it will turn on to the last used input. If no connection is detected, then it will go to the Co-Ax input, which is an always on connection.
Dear Samsung Tech,
I just bought a 55b7000 and it is terrific. My only problem is the source choice. As I only use a sat receiver on HDMI2 it is problem for me to choose the source list and go to hdmi2 everytime I turn on the tv. Is there a setting that tells the tv choose HDMI2 as primary source when I turn th TV on.