How to restrict OneNote Family room notebook from kids?


So I’ve set my kid up with a Microsoft account which he’s already been using for his Xbox login and email. He’s also under my Family so I can restrict access to certain sites, but my concern is that apparently as he’s under My family, he’d have full access to the OneNote Family room notebook that my wife and I use for everything, including from xmas gift shopping lists. How do I restrict access to this notebook that only my wife and I continue to have access and not my kids. Thanks!