The receiver is able to decode the Dolby True HD, Dolby Plus, DTS-Master Audio, and DTS-HD bitstream audio data.
Most Blu-ray players are able to send the audio bitstream to the receiver via the HDMI connection. When playing back the disc, select the audio format on the Blu-ray player. That selected audio format will be indicated on the front panel display of the receiver.
If after all following all these steps, the receiver is still showing PCM Multichannel, please check with the Blu-ray player manufacturer whether there are any updates available for the bitstream audio data.