I want to save my level progress in my quiz game

so this is my game, word quiz game. Every answer correct, it goes to next question. the problem is i have no idea how to save the progress of question so if i quit game or back to main menu, the question doesn't back to question #1 again. pls help me. here are the code :

 using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
 using UnityEngine;
 using UnityEngine.UI;
 
 public class QuizManager2 : MonoBehaviour
 {
     public static QuizManager2 instance; //Instance to make is available in other scripts without reference
 
     [SerializeField] private GameObject gameComplete, MainMenu, GameMenu;
     [SerializeField] private Text currentQuestion;
     [SerializeField] private QuizDataScriptable2 QuizDataList;    //Scriptable data which store our questions data
     [SerializeField] private Image questionImage;           //image element to show the image
     [SerializeField] private WordData[] answerWordList;     //list of answers word in the game
     [SerializeField] private WordData[] optionsWordList;    //list of options word in the game
     
 
     public Text CurrentQuestion { get { return currentQuestion; } }
     
 
     private int scoreCount = 1;
     
     private GameStatus gameStatus = GameStatus.Playing;     //to keep track of game status
     private char[] wordsArray = new char[18];               //array which store char of each options
 
     private List<int> selectedWordsIndex;                   //list which keep track of option word index w.r.t answer word index
     private int currentAnswerIndex = 0, currentQuestionIndex = 0;   //index to keep track of current answer and current question
     private bool correctAnswer = true;                      //bool to decide if answer is correct or not
     private string answerWord;                              //string to store answer of current question
 
     private void Awake()
     {
         if (instance == null)
             instance = this;
         else
             Destroy(this.gameObject);
     }
 
     // Start is called before the first frame update
     void Start()
     {
         scoreCount = 1;
         
 
         selectedWordsIndex = new List<int>();           //create a new list at start
         SetQuestion();                                  //set question
 
     }
     
    
 
    
 
     void SetQuestion()
     {
         gameStatus = GameStatus.Playing;                //set GameStatus to playing 
 
         //set the answerWord string variable
         answerWord = QuizDataList.questions[currentQuestionIndex].answer;
         //set the image of question
         questionImage.sprite = QuizDataList.questions[currentQuestionIndex].questionImage;
             
         ResetQuestion();                               //reset the answers and options value to orignal     
 
         selectedWordsIndex.Clear();                     //clear the list for new question
         Array.Clear(wordsArray, 0, wordsArray.Length);  //clear the array
 
         //add the correct char to the wordsArray
         for (int i = 0; i < answerWord.Length; i++)
         {
             wordsArray[i] = char.ToUpper(answerWord[i]);
         }
 
         //add the dummy char to wordsArray
         for (int j = answerWord.Length; j < wordsArray.Length; j++)
         {
             wordsArray[j] = (char)UnityEngine.Random.Range(65, 90);
         }
 
         wordsArray = ShuffleList2.ShuffleListItems<char>(wordsArray.ToList()).ToArray(); //Randomly Shuffle the words array
 
         //set the options words Text value
         for (int k = 0; k < optionsWordList.Length; k++)
         {
             optionsWordList[k].SetWord(wordsArray[k]);
         }
 
     }
 
     //Method called on Reset Button click and on new question
     public void ResetQuestion()
     {
         //activate all the answerWordList gameobject and set their word to "_"
         for (int i = 0; i < answerWordList.Length; i++)
         {
             answerWordList[i].gameObject.SetActive(true);
             answerWordList[i].SetWord('_');
         }
 
         //Now deactivate the unwanted answerWordList gameobject (object more than answer string length)
         for (int i = answerWord.Length; i < answerWordList.Length; i++)
         {
             answerWordList[i].gameObject.SetActive(false);
         }
 
         //activate all the optionsWordList objects
         for (int i = 0; i < optionsWordList.Length; i++)
         {
             optionsWordList[i].gameObject.SetActive(true);
         }
 
         currentAnswerIndex = 0;
     }
 
     /// <summary>
     /// When we click on any options button this method is called
     /// </summary>
     /// <param name="value"></param>
     public void SelectedOption(WordData value)
     {
         //if gameStatus is next or currentAnswerIndex is more or equal to answerWord length
         if (gameStatus == GameStatus.Next || currentAnswerIndex >= answerWord.Length) return;
 
         selectedWordsIndex.Add(value.transform.GetSiblingIndex()); //add the child index to selectedWordsIndex list
         value.gameObject.SetActive(false); //deactivate options object
         answerWordList[currentAnswerIndex].SetWord(value.wordValue); //set the answer word list
 
         currentAnswerIndex++;   //increase currentAnswerIndex
 
         //if currentAnswerIndex is equal to answerWord length
         if (currentAnswerIndex == answerWord.Length)
         {
             correctAnswer = true;   //default value
             //loop through answerWordList
             for (int i = 0; i < answerWord.Length; i++)
             {
                 //if answerWord[i] is not same as answerWordList[i].wordValue
                 if (char.ToUpper(answerWord[i]) != char.ToUpper(answerWordList[i].wordValue))
                 {
                     correctAnswer = false; //set it false
                     break; //and break from the loop
                 }
             }
 
 
             //if correctAnswer is true
             if (correctAnswer)
             {
                 
                 scoreCount += 50;
                 currentQuestion.text = "Score:" + scoreCount;
                 Debug.Log("Correct Answer");
                 gameStatus = GameStatus.Next; //set the game status
                 currentQuestionIndex++; //increase currentQuestionIndex
 
                 //if currentQuestionIndex is less that total available questions
                 if (currentQuestionIndex < QuizDataList.questions.Count)
                 {
                     Invoke("SetQuestion", 0.5f); //go to next question
                 }
                 else
                 {
                     Debug.Log("Game Complete"); //else game is complete
                     gameComplete.SetActive(true);
                 }
             }
         }
     }
 
     public void ResetLastWord()
     {
         if (selectedWordsIndex.Count > 0)
         {
             int index = selectedWordsIndex[selectedWordsIndex.Count - 1];
             optionsWordList[index].gameObject.SetActive(true);
             selectedWordsIndex.RemoveAt(selectedWordsIndex.Count - 1);
 
             currentAnswerIndex--;
             answerWordList[currentAnswerIndex].SetWord('_');
         }
     }
 
     
 
 }
 
 [System.Serializable]
 public class QuestionData2
 {
     public Sprite questionImage;
     public string answer;
 }
 
 public enum GameStatus
 {
    Next,
    Playing
 }