No surround sound from UBP X800

[lgcebr]

Until last Friday I had my BluRay player /A1 TV / STR DN1060 working perfectly playing 5.1 sound through home cinema speakers.  The A1 TV developed a fault and was replaced by Sony with the AG9.  All the labelled wires/HDMIs simply transferred into the same corresponding sockets/ports on the new TV.  The new TV is set to play on the audio system. So everything should work but it doesn’t and I’d appreciate any ideas.

However now if I play a BluRay the AVR first shows BD source correctly but as soon as the BluRay starts playing it changes to show TV and plays only in stereo.  
I can’t find any setting on the new TV which would cause this to happen.  Any ideas gratefully received.

I had hope a straight swap from one TV to another using same labelled sockets would be easy!

[Sonyvores]

you need to allow TV to passthrough signal in bitstream, have you done that within the settings?

[lgcebr]

Thanks for replying.  I presume this means  the settings on the TV?  Can you point  me in the right direCiting on the settings please?  Which section / option should I look at?

Thanks again