Echo Dot as TV bluetooth speaker

[Griffin]

I have bluetooth headphones and my Echo Dot bluetooth acting as speaker for my TV. It all works fine. However when I am listening on my headphones I don't want the Echo Dot speaker on as well.

I say "Echo Disconnect" which works. But after a short while the Echo Dot says it is connecting to the TV audio. How do I stop it re-connecting automatically? I want it to only connect when I tell it to (by saying Connect, which works fine).