Anemones are quite the individual. They can appear quite healthy on the outside and be almost completely dead on the inside. Most anemones take weeks or months before death finally sets in. By the time you see something awry, it's usually too late. Anemone behavior is a bit hard to understand, but there are certain staple issues that one should look at on a daily basis.
One of the first things that anemones require is lighting. They host zooxanthellae and these symbiotic algae require high lighting in order to produce the sugars that the anemone uses to feed itself. However, in nature, solid food does come into contact with the anemone, so feeding them by hand is a good idea to supplement its dietary needs.
LTA's and BTA's are now the most common found in home aquariums. They have both been good at adaptability in the home aquarium, as far as anemones goes. In other words, they have been the easiest to maintain, but anemones are one of theose marine animals that are better left in the ocean, unfirtunately. They live in very shallow waters and require high, intense lighting.
Your anemone keeps moving around because it isn't happy, or can't find a spot to get happy. Some LTA's will took root in a rock crevice, but the BTA is more well known for that. Most LTA's will root in the sand bed, maybe wedged between the sand and a rock. It sounds as if it is looking for a home and is having hard time doing so. If the anemone doesn't find a spot, it will stress itself out, constantly raoming the tank. Also, if you have any corals in the tank, be aware. Anemones can be destructive and sting everything in it's path looking for a home.
If you find yourself constantly trying to put the anemone in a spot, I would consider returning the anemone or find another home for it.
Is the anemone opening up all the way and closing at night. Is the mouth tightly closed or gaping open. Have you checked the foot(base) for any tears or injuries?
Post a pic if possible.
HTH!