Device settings can be found here, https://www.brewersfriend.com/homebrew/profile/device_settings
You can change the chart period with the drop down. You then click the arrows left or right of the days to pan backwards or forwards through time.
You can export readings in CSV or JSON.
You can edit brew log under the Brew Log tab but not in the chart. You can however edit any entries that were sent from devices in the edit view.