Each turn during the upkeep phase, a player may adjust their investigator's skills a number of "stops" equal to their Focus. For example, if an investigator with Focus of 2 may adjust their Speed up 2 stops, or their Speed up 1 stop and their Fight up 1 stop.
Each Skill value appears in a pair - Speed is paired with Sneak, Fight with Will, and Lore with Luck, so that in adjusting one skill value up, the investigator is adjusting the value of the skill paired with it down.
Exception: During game setup players may place their Skill sliders on any of the stops on their skill tracks. The initial setup does not follow the normal restrictions for Focus.