My iPhone 6 Plus was disabled (connect to iTunes). So I restored my iPhone. But after restoring my iPhone to the latest iOS 12.1.4, the system is unstable and has many problems. My iPhone 6 Plus used to have many big or small problems(iOS 10, iOS 11), and people advised me to "Do a Clean iOS Install". Because the iPhone was disabled, and I could not "Remove All Content and Settings" before restoring the iPhone. Is this the reason that the just installed iOS 12.1.4 still cannot fix the previous problems, and is unstable? Should I "Remove All Content and Settings", and restore the iOS again? Thanks.