Graph filters change one graph, without affecting the rest of the dashboard. They sit at the top of the graph.
Metric: what you measure. For example Average Arrival Delay, On-Time Departure Rate, Average Departure Delay, or On-Time Arrival Rate.
View by: how time is grouped. For example Date, Week, Month, Quarter, Year, or Day of Week.
Example
Switch a punctuality graph between arrival and departure with the Metric filter. It is the same graph: there is no need for ten near-identical ones.
To filter all the data of a dashboard at once, use the header filters instead. See How do filters work in Analytics?