The shower valve can set up so that no matter how far the handle is turned to the hot side it will not go past a certain point and so the water will not get too hot.
Setting it up is easy but you may have to try it a few times before you get the temperature where you want it. The good thing is the water can be on while you set up the scald guard.
The handle and handle adapter have to be off. Then to turn the temperature of the valve down move the outermost white piece to the right to limit the hot. How many splines you move will be up to how much you want to restrict the hot water. Just set it and try turning the valve on with the handle adapter loosely in place until you get it set where you want it. On the contrary if you want hotter water then move the outermost plastic piece to the left a few splines and this should give you warmer water.
Note: Always be careful when testing the setting of hot water to avoid getting scalded. Turn the hot water on slowly so you can stop when it becomes too hot.