Your anemone is moving because he does not like the place you put him, either too much flow, not enough flow, too much light not enough light ect.. They will move around until they find a suitable location for themselves. This is normal and putting him back everytime is just stressing him out even more. Let him find a spot he likes and unfortunatly you have to adapt to his likeing, weather it be out of site, the back of the tank ect.. Or you need to change the tank around to suit his needs