navigationItem.hidesBackButton = YES

let backButton = UIBarButtonItem(title: ">", style: .Plain, target: self, action: #selector(backTapped))
navigationItem.rightBarButtonItem = backButton

I use this way for change back button position.

   //put this code in viewDidLoad()


   navigationItem.hidesBackButton = true
   navigationItem.rightBarButtonItem = UIBarButtonItem(title: " > ", style: .done,target: self, action: #selector(addTapped))


   //function to handle back navigation

   @objc func addTapped(){

    navigationController?.popToRootViewController(animated: true)
    }