When the checkbox is ON, it will apply the default settings (such as left/right, upper arm/wrist, and posture) to all past blood pressure records that are missing this information.
Note: Once applied, you can still edit records individually, but you cannot perform another batch edit.
If you want to revert to the original state, a backup file will be automatically created at Downloads folder on your device at the time of execution, so you can restore it to undo the changes.