Cedar Creek gray water tanks

We recently purchased a 2018 Cedar Creek Hathaway Edition 36CK2. After a couple outings I discovered that the shower and kitchen sinks drain into 1 gray tank and the bathroom sink and washer,which we don't have, drain into the other gray tank. Needless to say, the kitchen sink/shower tank fills quickly and the other tank (bathroom sinks) has hardly anything in it. Wondering if anyone else has this problem and if so, how did you correct it?