HT-RT3 no 5.1

[PeteZilla]

Spoiler

Hi bought this item HT-RT3 to replace our STR-KSL5.
I have KDL-40CX523 tv and connected is a BDP-S185 Bluray player.
I only have 4 HDMI connections and all 4 are in use.

1 virgin cable box.

2 fire stick

3 x box

4 blu ray.

so I have connected the HT-RT3 via optical audio cable. I am struggling to achieve 5.1 sound I have managed to get 5.1 from my virgin tv box when I switch off the tv speakers and set it to home theatre.

But I can not get the Bluray to output in 5.1 as when I check the stream in the Ht-rt3 audio settings while playing a bluray it only displays LPCM which is just a 2 channel broadcast. I have adjusted the bluray audio settings as recommended via the internet but still no joy.
Do you know how I can achieve 5.1 audio from the bluray player on my old system it was connected via the digital coax but that option is not available on the new system, and I am currently feeling that by upgrading our soundsystem I have actually got a poorer quality sound from our bluray.
Can you help? As I have exhausted my knowledge.
Thank you.

[PeteZilla]

I have tried connecting via hdmi arc and still only get 5.1 via the cable box. 

[PeteZilla]

These are my current blu ray audio settings. 

[PeteZilla]

TV audio settings