I have a PC with windows 8.1 I connect a TV to it using HDMI. I selected the HDMI device to be my default device. I am able to play video and audio on TV without any problem. However, when I turn off the TV, the audio does not switch back to the PC speakers. (I have to either unplug the HDMI cable or chose the speakers to be default device). Shouldn't the sound/audio switch automatically when I turn off the TV? Thanks.