To access Account Settings, touch the "Account" icon at the bottom right of the app. Then touch the widget at top left to access editing ability, and settings.
Choose "Edit" to edit your personal information and photo.
Choose "Settings" to control your cellular data for syncing, choose units of measure, choose security options, and log out of your Diary.
If you want to use your cellular plan when syncing data, slide the button to the right (this is not advised unless you have a large data plan). If you want to restrict background syncing of your Diary data to wifi, slide the button to the left to toggle off.
For measurements, the dark box indicates which measure you are using, the metric measures or the imperial measures used in the U.S.
In Security, you can choose a Passcode and Touch ID to open your app each time. Here you will also see your options for support in the Diary app and the button to LOGOUT of your Diary.