The sofa had better lean against the background wall. This means that there is a backer and a bright future. If the living room is big enough, it is best. If there is not enough space, you can lean against the wall with a straight sofa. Don't lean behind the sofa. If you can't stand against the wall because of space, you can put a row of cabinets in the back. Anyway, you must rely on the sofa, so that people can sit down and be stable. Besides, the sofa is not suitable for facing the door.