This is the thermostatic(?) mixing valve underneath my bathroom sink. When I bought the house new, I was told that it was a mixing valve for the Tub to prevent scalding. How do I adjust the mix? I understand that I need to turn the nut(?), but, (1) which way should it be turned and (2) which nut? There are two nuts I see, labelled "A" (small) and "B" (large) in the photo. Note that location (A) in the photo says "C" on it. (Maybe this means it adjusts the cold flow?)
I desire hotter water, which way do I turn it?
Location: Western United States. Plumbing was done in 2016.

