100 is just the default value, you need to set it to whatever you have it to in the game. The ADS sensitivity is a product of all three values; Mouse Horizontal Sensitivity, Aim Down Sight Horizontal Sensitivity and X Sensitivity. But only Mouse Horizontal Sensitivity and X Sensitivity are calculated, the Aim Down Sight Horizontal Sensitivity can basically be anything as long as it is in range, but you can in most cases just set it to the same value as the Mouse Horizontal Sensitivity.