If the blue and white icon in question is on the left side of the notification bar, you can swipe that down and see what notification it pertains to. That will likely answer a lot of your questions.
And what do you mean by "supplementary settings?" That's not standard nomenclature and there are settings all throughout the phone and apps, so I have no idea what you are referring to. You also can't delete a setting, so are we to assume you mean reverted to their defaults?