Tap "More Settings" when adding a new task to customize note settings.

Notes are set to be empty by default. If you would like to add additional details to a task you can use the notes feature. Go to the Settings tab on the Menu page and tap "Note History" to see all the notes you've associated with various tasks. To delete your note history, simply tap "Delete all". Please be aware: your note history cannot be recovered once it has been deleted.