That valve is to regulate water in your livewell. Leave it on empty until you’re ready to fill it, then switch it over to auto which will close it, keeping the water in the livewell. Turn back to empty when you want to drain the livewell. Not sure if yours has a pump out livewell option but that shoots the water out of the livewell too. There are other posts on here regarding livewell operation as well. Hope this helps.
