The Overview report provides a snapshot of your key metrics.
Here is an example of this report:
You can change the date range for the report by clicking the calendar icon on the top right side. You can also create a sticky filter that spans different reports to see how a segment is performing across all mobile reports. For more information about creating a sticky filter, see Add sticky filter.
You configure the key metrics for this report while creating the app. For more information, see Configuring your app.