When you pair Apple Watch with your iPhone and .
Change the time span displayed in the graph: Swipe the graph left or right.
See details about a moment in time: Touch and hold the graph, then drag to move the selection.
View details about average exposure: Tap Show More Data, then tap Daily Average.
View a line representing average exposure: Tap Exposure below the graph.
View the high and low range: Tap Show More Data, then tap Range.