Passenger rear brake piston

Turn it the other way. I've never seen arrows on a brake caliper so how do you know it's pointing in the direction to retract the piston or adjust it out?

Ford is the only manufacturer that has refused to give up this miserable design and switch to what Chrysler has always used. If the piston turning tool doesn't work you can unbolt the parking brake lever, use a wrench to turn the adjusting bolt about 1/8 turn, then push the piston in a little with a c-clamp. Don't use a lot of pressure. After it moves in, turn the adjusting screw some more, then push the piston in some more. Repeat that until the piston is fully retracted. If you run the adjusting bolt in too far at once it will expose the rubber lip seal. The seal can get ripped on rust on that bolt or it can allow some air to sneak in.

Once it's installed you will have to exercise the parking brake repeatedly to get the pistons to adjust out. They won't do that automatically by pressing the brake pedal like the front ones will. Ford has a real big problem with parking brake cables rusting tight in as little as a year. If that is the case you can use a large pliers to work each lever right at the calipers.

Also be sure to never push the brake pedal down more than half way to the floor when you work the front pistons out. Doing so can damage the master cylinder if it's more than about a year old.

That's why I said to not use a lot of pressure on the c-clamp. I never allowed my students to use a c-clamp on any caliper but I suggested it to you because you have an unusual situation. Too many people think c-clamps are necessary and acceptable to retract front pistons. In fact, if you NEED a c-clamp to make the piston move, there is a ring of rust or dirt around the piston or there's debris built up in the caliper. Replacement front calipers are so cheap today we can't even rebuild them cost effectively.

The purpose of the c-clamp in back is not to force the piston against that adjusting screw. That is what will destroy it. If you unbolt the parking brake lever, then turn the adjusting screw with a wrench, that screw is going to screw into the piston. That is what will allow you to push the piston back into the caliper a little at a time. I typically do that by reattaching the caliper to its mount with the rotor in place, then I use a medium flat blade screwdriver to slowly pry the piston back in. That's how I retract all front pistons before I ever take the calipers off. If a piston won't retract on the front, the vehicle gets two rebuilt replacements.

The tool you're using puts just as much pressure on the piston as a c-clamp. Also, those threads they're warning about damaging are what applies the pressure when you apply the parking brake. That pressure is going to be a real lot higher than anything you can do with a clamp. Since you can't fit one in there anyway, use that tool after you thread the screw in a little. That screw will also have to turn counter clockwise if the piston does.

Keep in mind too that Ford had some vans and trucks that had the right parking brake cable run all the way to the rear bumper and come in from the back. Those calipers were different than when the cable comes in from the front like normal.