Just wondering How to turn
unruly is right....if your shower valve is the model that has those isolation valves built into it...If yours does, you will have no problem seeing them once the cover plate is off...If there is no sign of any bulging fittings on each side of the valve, with a slotted drive stem in the middle of each one looking back you, directly in the eye, then you have to take a different approach to solving the pressure problem.
That approach will cost you the price of a new shower head...because that's your only remaining option, (short of hiring a plumbing contractor to install a couple of flow reducing fittings or isolation/metering valves on your supply piping)(a five hundred dollar bill will buy that option), available for a FIY project. A new head can be purchased for under 10-12 bucks....just make sure to take your old one with you when you go to buy the new one....this will identify the means in which your shower head attaches to your shower arm pipe. It wouldn't hurt to pick up a small jar of pipe thread compound or Teflon tape too. Some shower head re-attachment applications require a pretty snug fit to prevent leaks at the connection joint. You see, there will be more pressure on that connection now, because the new shower head you bought has a restrictor built into it, thus your water pressure issue is resolved, but that added resistance also causes higher pressures in the shower arm and piping supplying it inside the wall. That is why you should use thread compound or Teflon tape on the threads when you re-install the new head. ...And also, the threads on the shower arm have been used once already, which deforms the threaded area slightly, making for a loose-er fit when re-used. The Teflon tape can take up the space by adding a couple extra wraps on the threads. And before attaching the new head, paint a light coat of pipe thread compound on top of the Teflon tape, (brush it on in a clockwise direction only...the same direction you rolled the Teflon tape onto the threads)(and take care not to get any pipe thread compound inside the shower arm....the flow orifice in your new shower head will be sensitive to any debris that try to pass through it)(it will be prone to clogging)(and it will continue to slowly clog as time goes by...another reason to do the in-line valve option,.... and require being flushed out occasionally), and that will surely give you a good tight seal. Not to be too commanding, If I could Just suggest one more thing.....Please use a smooth face wrench, (like an open end wrench or adjustable cresant wrench) to tighten chrome finished fittings and pipe. If you have to use channel locks or pliers in the place of a strap wrench, get one of your best wash cloths and wrap it around the pipe or fitting before gripping it with the jaws of the pliers. If you have a spouse...you might want to keep the wash cloth thing between us guys, but it really needs to be a cloth wit a thick layer of material, otherwise the pliers will pinch right through and be useless....if you have a leather shammy....that would work the very best...
Well I lied....there is one other option, if your real attached to your present shower head, you could purchase an in-line shut-off valve and install it directly behind your shower head, on the shower arm. It would have to be an in-line globe, (best)-needle, (good)-or ball, (okay), valve type of configuration, so you could adjust the flow to a more suitable volume/pressure. Because the new shower head will not be adjustable and you will have the pressure reduced to the set gallons per minute setting that the head was designed and manufactured to flow at. Get a nice chrome plated brass bodied in-line valve, with a globe type valve design and install it just up stream, (directly behind), your shower head and this will be the best DIY option you could take. I would definitely opt for this method to reduce my water pressure out of the shower head....because it not only allows me to adjust the pressure to just the way I like it, but it also makes me a proactive part of conservation of our fresh water supplies, by allowing me to easily turn off the water flow while I lather up with soap, then easily turn it back on to rinse.....This option may cost more around 30 bucks, and it may prove to add a degree of difficulty toward finding the right in-line valve, but I think it will pay for itself in the short/longish run. If you have a "mom and pop", locally owned hardware shop left in or around your town/city, I would suggest looking for the "best" in-line valve there. A shower head in-line metering/shut off valve...chrome plated brass body, 1st-globe valve configuration...2nd-or needle valve....lastly-ball valve configuration, it must have a stainless steel stem and handle/lever for easy operation, and the connection configuration must be 1/2" FIPS inlet side and 1/2" MIPS outlet side for best results, mechanically and aesthetically. You find yourself this exact valve and it's a done deal. Or just get a new head and bing bang bam...pressure problem fixed.....just like that. good luck and may the Plumb Gods smile upon your efforts.....
ps....peel off the excess Teflon tape and wipe off the excess pipe thread compound when you finish attaching you new head/in-line valve. Beautiful...pss...there are a few web based retailers that sell hard to find fittings and valves ...like the in-line valve I've suggested...I can only remember a part of one of the retailers names....McMasters and???. that should get you there.