Voice authentication on HomePod

Just got a HomePod and feeling very frustrated with it. 1) how do I turn off voice authentication? It is constantly asking my husband and me who we are no matter how many times we authenticate ourselves. 2) we want one shopping list that all members of the house can add to. It only needs to go to my phone but when someone other than me adds something to the list we want it to go to the shopping list on my phone. How do we do this?