yeah if you dont have clowns that host it i found that they do better if feed weekly. I have a RBTA goe it prob 2 months ago, was about the size of a tennis ball now its about 7in round. I have 2 clowns that host it but i still give it a piece of shrimp every now and then if i see my clowns being lazy and food hogs. Hope yours fines its happen spot, I know the ones i have the base hates light, all of mine has put there base inbetween 2 rocks and sorta reaches over them and spreads over rocks. but you can never really move it were you want it. it will go were it wants.
From what i have been told:
If a nem detaches and moves its often due to water quality, it deataches and floats to a newer cleaner spot in the ocean, in the aquariam this results in a short death through the powerhead.
If it seems to be crawling over the rock its trying to find the light and flow it wants. but will stay attached. My current nem was attach on a rock when i bought it and crawled about 5 inches higher up and settled there for the past 2 months. took it 2 days to find a spot that was 5 inches away.
HTH