These are the instructions to reset the pressure higher or lower than the initial factory settings.

If the pressure control bolt (-A) is turned clockwise, the right-
  side scale on the front will go up and the pressure will
  decrease.
If it is turned counter-clockwise, the right-side scale will fall
  and the pressure will increase.
If the pressure is reset to more than 6㎏/㎠, the safety value
  may open. The safety value must be replaced with one that is
  2㎏/㎠ greater than the setting pressure.
The differential pressure bolt (-B) is the on/off control bolt for
  the pressure differences. When it is originally delivered, it is
  set at the lowest value (0.7㎏/㎠, zero on the scale). Please do
  not modify this.