When wanting to export data from a stream you need to select the drop down menu located in the top right of the dashboard.
Then press EXPORT STREAM, then a pop-up will appear.
If you want to export the data from longer than 7 days select the change tab and choose one of the options from the drop down list.
If you want to customise the dates you want to export, select custom from the drop down menu where you can specify the dates you wish to see an export of (see image below).
Once you have made these changes select the green Export tab.