Host family placements come with a document about expectations. It covers meals, laundry, guests, and quiet hours. It does not cover the lift, which is where I have made all my mistakes.
The unwritten rules
You hold it for the neighbour on the third floor. You do not use it for one floor. You greet whoever is already inside, every time, and the greeting is not optional.
Small things, and the building notices all of them. I got three weeks into silently riding up with people before my host mother gently explained that I had acquired a reputation.
The handbook tells you the rules your hosts can write down. The building teaches you the rest.
I greet everyone now. The woman on the third floor has started saving me bread from the good bakery, so the system works.