When working with young learners I seldom change the seating arrangement since I support the idea that students need to get used to a certain "routine" so that it is easier for them to know what to do in each class. Furthermore, I usually allow them to sit in a way in which they feel comfortable, it is usually on the floor.
One technique that I consider highly effective is to check answers through games they like, in that way all students are encourage to finish the activities as soon as possible so that they can play.