Hi Prp,
I think you misunderstood my problem (or I may not explained it correctly).
Muting the computer will not make it stop trying to connect to my receiver. Of course I can forget of disconnect my receiver but this is not what I asked.
I work on my computer and it's sound connected to the receiver via BT. I wish I could connect is with an optical cable but I have a new computer that comes without an optical cable and I still didn't figure it out how to connect to it to the cable so I connect it via BT.
When I play a sound on my computer it will auto select the receiver source to BT.

I then go to watch TV and set my the source to "Optical 1".

But then, the computer gets an email and want to play a sound so my receiver auto switch it source to BT. I thought that if at the end of my working day, I can switch the sound source on the computer - for instance to headphones , but it doesn't help. Unless I disconnect the BT connection, it will keep choose it and my receiver will change its source to BT. This is annoying.
I want to cancel the option that the computer will auto select BT and stick to my latest source selection of Headphones. I don't want to disconnect and reconnect to BT every day.
Thank you very much,
Shlomit