By default the time period shown are the last four weeks when you contributed to a project.
To choose a different time period, click the Start Date dropdown or the End Date dropdown in the right corner of the parameters bar.
Changing the reporting interval
The reporting interval controls how the reporting period is measured presented on the diagrams.
By default it shows weekly dates.
You can change that to be daily, weekly, monthly and quarterly.
Compared to others
There is a check box "Compare" which controls if your performance is compared to others.
By default it is checked. That leads to displaying on the diagrams the others' data in grey.
If you want to see your temporal performance alone then uncheck the box.
Searching
In order to refresh the diagrams to reflect the new time period you can click the Search button with the lens icon on it.