On the top right hand side of the analytics page you can change the time frame between 1 Day, 1 Week, 1 Month, 3 Months and 6 Months.
You may also change the time frame for an individual analytics feature from the top right of the enlarged graph.
The enlarged chart will open on the time-frame selected in the dashboard
You may want to change the time frame within the enlarged chart.
Changing that time frame will affect only the enlarged chart.
When closing the enlarged chart even if the time-frame has been changed it will have no impact on the dashboard (neither to the small version of the chart in question or any other metrics on the dashboard)