A shower mixing valve typically will need to be adjusted after you first get it. Luckily, this is something that you will be able to easily do yourself with very few tools and time.
Step 1 - Remove Handle
In order to adjust the mixing valve, you will need to first remove the handle so that you can get to the inner screws. The handle is easily removed by loosening the screw that is keeping the handle in place.
Step 2 - Adjust
Once you have removed the handle, you will see another screw that goes over the valve stem. This screw is what keeps the water from getting too hot or too cold. In order to adjust it, you will simply need to loosen the screw by just a couple of turns.
Step 3 - Test
Once you have loosened the screw a little bit, you will need to check it with the handle. You may need to do this a few times. Do this until it is at the temperature that you want it to be at. From there, put the handle back into place and enjoy your newly adjusted shower mixing valve.