All of the reports shown in the reports section are shown for a given date range. This allows you to ask the question: "What programs did I use yesterday?" as easily as "What programs did I use last month?"
In order to change the relevant date range, you would use the Date Settings window which can be accessed by clicking on the "Set Date" button. Once a date range has been set, the date range will appear in the Date Settings box. Note that the default date setting is for "All Available Data".