Apologies in advance if I have posted this in the wrong place.

I have recently downloaded Whatsapp for my iPhone. I want to make sure my chat history is private.

Does my history automatically stream to somewhere on my iMac? (This is a shared computer and wouldn't want this to happen)

Also of I avoid doing a back up of my message history on iCloud and I choose to delete messages are they completely deleted.

Ideally id prefer, as long as no one has access to my iPhone my message history is private.

Many thanks