Sorry if that wasn't the answer you were looking for, but it's still true. Healthy anemones are attached to a surface. Failure to hold on means that something isn't right. The reason why it's currently free-floating is to find a better place to live. In the wild, there'd be a chance of the current blowing it to more hospitable ground.
If this is your 75 gallon, it's a bit more than 5 months old, assuming that you dated your previous threads accurately. Not long enough for an anemone, especially with dry rock. Do some more research in the future, one of the fundamentals of anemone keeping is that you need an established tank.
There isn't a way you can "force" it to settle. Despite not having a brain, anemones have a mind of their own. Try "fencing it in" with some small pieces of rock rubble against the main rockwork. You can also wedge the foot in a gap between the sand and rock. I see a few places in there where you could do that. If it's going to attach, it will.
Your maroon clowns might also be bothering it. Maroons are brutish little things, they can very well harm an anemone. They could be preventing it from attaching by bothering it. I like to add clownfish after an anemone settles in. You might want to put them in an acclimation box for a few days while the anemone (and you) sort things out.
In order to speed up the process of the tank becoming habitable for the anemone, you might add some real live rock to the tank. Not any of that LFS stuff which was dry two weeks ago, there are a few places which sell real aquacultured live rock straight from the ocean.