When viewing the Sprint Burndown gadget from the dashboard, the option is and should only be to refresh and minimize:
To edit it you have to go to Administration > System > System dashboard. There it will look like this and be editable.
Hope that solves your issue!
Connect with like-minded Atlassian users at free events near you!Find an event
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no Community Events near you at the moment.Host an event
You're one step closer to meeting fellow Atlassian users at your local event. Learn more about Community Events