When you are logged in to the host environment, you can go to your listing. Here you will see an overview of all your listings and you can choose the right one. Then you will see the details of the listing and you can click on the pencil-icon on the top right. This gives you access to edit details. In the edit mode there is a tab with Booking Settings. Here you can specify the house rules. When you have adjusted this to the desired house rules, you can save the edit and it will automatically become active for your listing.