How can I make a swift multiple questions quiz so the questions do not repeat themselves?

I do not have any experience with programing. I have done this looking at youtube videos for a couple of months. I will really appreciate if someone can please help me. When I run the code with the simulator it repeats the questions several time before the next new question is presented. I would like it to run so it presents one question without repeating the same question over and over. Below please find the code.

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var QuestionLabel: UILabel!

    @IBOutlet weak var Button1: UIButton!

    @IBOutlet weak var Button2: UIButton!

    @IBOutlet weak var Button3: UIButton!

    @IBOutlet weak var Button4: UIButton!

    @IBOutlet weak var Next: UIButton!

    @IBOutlet weak var LabelEnd: UILabel!
    var CorrectAnswer = String()


    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        Hide()
        RamdomQuestions()
    }

    func RamdomQuestions () {
        var RandomNumber = arc4random() % 4
        RandomNumber += 1

        switch (RandomNumber) {

        case 1:
            QuestionLabel.text = "Hola familia, Cual es mi nombre? "
            Button1.setTitle ("Cesar", forState: UIControlState.Normal)
            Button2.setTitle ("Karlos", forState: UIControlState.Normal)
            Button3.setTitle ("William", forState: UIControlState.Normal)
            Button4.setTitle ("Chiqui", forState: UIControlState.Normal)
            CorrectAnswer = "2"

            break
        case 2:
            QuestionLabel.text = "Hola famili, cual es mi apellido? "
            Button1.setTitle ("Perez", forState: UIControlState.Normal)
            Button2.setTitle ("Carvajal", forState: UIControlState.Normal)
            Button3.setTitle ("Garcia", forState: UIControlState.Normal)
            Button4.setTitle ("Sanchez", forState: UIControlState.Normal)
            CorrectAnswer = "1"

            break
        case 3:
            QuestionLabel.text = "Quien hace la lachona mas rica? "
            Button1.setTitle ("Willy", forState: UIControlState.Normal)
            Button2.setTitle ("Mario", forState: UIControlState.Normal)
            Button3.setTitle ("Karlos", forState: UIControlState.Normal)
            Button4.setTitle ("Juan David", forState: UIControlState.Normal)
            CorrectAnswer = "1"

            break
        case 4:
            QuestionLabel.text = "Quien hace las tartas mas lindas"
            Button1.setTitle ("Jili", forState: UIControlState.Normal)
            Button2.setTitle ("Carvajal", forState: UIControlState.Normal)
            Button3.setTitle ("Garcia", forState: UIControlState.Normal)
            Button4.setTitle ("Leidy y Liz", forState: UIControlState.Normal)
            CorrectAnswer = "4"

            break

        default:
            break
        }
    }

    func Hide (){
        LabelEnd.hidden = true
        Next.hidden = true
    }

    func UnHide () {
        LabelEnd.hidden = false
        Next.hidden = false
    }

    @IBAction func Button1Action(sender: AnyObject) {
        UnHide()
        if (CorrectAnswer == "1") {
            LabelEnd.text = "Correcto"
        }
        else{
            LabelEnd.text = "Falso"
        }
    }

    func Button2Action(sender: AnyObject) {
        UnHide()
        if (CorrectAnswer == "2") {
            LabelEnd.text = "Correcto"

        }
        else{
            LabelEnd.text = "Falso"
        }
    }

    func Button3Action(sender: AnyObject) {
        UnHide()
        if (CorrectAnswer == "3") {
            LabelEnd.text = "Correcto"
        }
        else{
            LabelEnd.text = "Falso"
        }
    }

    func Button4Action(sender: AnyObject) {
        UnHide()
        if (CorrectAnswer == "4") {
            LabelEnd.text = "Correcto"
        }
        else{
            LabelEnd.text = "Falso"
        }
    }

    @IBAction func Next(sender: AnyObject) {
        RamdomQuestions()
    }
}