Control what data to be shared with friend in talks

I'm just wondering if there's a control toward what data would be shared with friends’ talk? I’m honestly a bit confused on how should i position This app - if it should work as my second brain, i would like to dump everything in life, including those very personal and intimate thoughts, So it truly is gonna be a second me. However, i don't nessisarily want to share those thoughts with my friend and of course not the public. So when we create talks and when our friends or other people talk with our second me, what data would be shared with them? Do i have any control toward the data and info to be shared? This could really change how do i use the app.