Whenever I join a Multiplayer session, the audio just shuts off!!! Please help. P.S If I have to clear cache or anything very risky or something deleting every Xbox files, I will not do it. Please just share something easy 
It’s not switching off, its lowering the volume. Change the chat settings on your console.
Go into Settings - Display & Sound - Volume - Chat Mixer - Select “Do Nothing”
That should solve the issue.