Time Tool

Use this tool on any graph to choose the date and time range that suits your purpose.

Use the settings on the left to choose a recent period of time. Or use the calendar to choose a specific date and time for the start and end of the range. You don't actually need to pick Custom Range - you can just click on the calendar and you will see "Custom Range" highlighted. Be sure to hit Apply and the time period covered by the graph will change. 

The current range of any graph is shown at the top right of the graph:

Click on the down arrow (or anywhere on that label) to pop out the time picker.