Most if not all red dots have the adjustments labelled for which direction you need to move the point of impact.
For example, if the dot is on the bullseye and your shots are grouping consistently low and center, you would turn the adjustment in the direction marked for "up"
Thinking about which way the dot is actually moving in relation to where it was is unnecessary. Good to know for a mental exercise, but not practical in achieving your goal, because you still would be faced with an adjustment marked as "up" but does not refer to actually moving the dot up, because as others have mentioned, if you do all the figuring and decide you need to move your dot up, you would turn the adjustment in the "down" direction anyway.
tl,dr- Up/down and left/right indications on the adjustments on red dots are referring to the direction the point of impact will shift