The Refresh Interval controls how often an open dashboard will refresh. Dashboards are automatically updated once daily at 3am in the timezone selected in your project settings. When individually opened, Dashboards are also updated at the Refresh Interval selected.
To select a Refresh Interval, click on the Refresh Interval menu at the top of the dashboard, which is set to Every Hour by default. You can toggle between Every 15 Minutes, Every 30 Minutes, Every Hour, or Every 2 Hours. A timestamp displaying the date and time of the dashboard's most recent update is located at the top of the dashboard, to the left of the Refresh Interval menu.