Water on/off is in the wrong position after changing the moen cartridge in my shower

Moen posi-temp cartridge. 1222/1222B
-or-
Moen 96988 Cartridge Repair Kit Posi-Temp 1 Handle tub/shower

https://www.moen.com/shared/docs/exploded-parts-views/82000pt.pdf

Best to have the Moen Cartridge Puller.

http://pro.moen.com/1-handle-replacement-cartridge-posi-temp/_/R-TPORTAL-ALL%3A1222B

defective part

you cannot use any other cartridge posi temp only. remove flow restrictor in hand held

Remove the handle and see if it will turn off without the handle and if it will reposition the handle alignment and your good to go. If no the cartridge will need to be replaced.

I'm not aware of any problems with non moen replacement parts being the cause for a water hammer problem. Start with the simplest and cheapest correction which is using a moen replacement cartridge. If the water hammer persists then you may have to install a water hammer arrester in the plumbing system. This is basically a shock absorber in the plumbing system to stop the effect of water hammer. An arrester will cost you around $10 to $15 at your local plumbing supply shop. If you are not comfortable soldering copper then you will want to hire a licensed plumber to complete the work for you.

I had the same type of problem with an older toilet in my house. It developed a water hammer when it shut off after filling the tank. I replaced the fill valve with a generic universal replacement for about $10 and it stopped. Again sometimes the simplest fix will work. Let me know how it works out.

I just had the same experience, except I used a non-Moen cartridge. (It was from Ace Hardware, and Ace told me that Danco was the manufacturer.) When I pulled the cartridge back out, one of the two hard plastic seals on the side of the cartridge had torn, presumably on the sharp metal opening on the water supply pipe. I'm guessing there's something wrong with one or both of the seals on your new cartridge.

Your Moen valve is equiped with an anti-scald device (as part of the valve cartridge) which prevents someone from getting scalded by hot water if there's a sudden demand for cold water, i.e. a toilet flush, washing machine filling, etc. Fortunately Moen stands behind their products and will provide a new cartridge.
Contact Moen and describe your problem.

You have to remove cartridge and rotate 180 degrees then re-install. Was it removed or replace lately?

replace the cartridge if defectis not obvious.

check the water supply to and from the hot water heater