How to Display high score using GUIText

Well, i'm pretty new with unity. I got a problem to display highscore. The score was display everytime enemy were shot. I want to display the highscore everytime the game end and be able to update everytime i got a new highscore. The score system using the GUI text. The example below.

Score:

Highscore:

To display the score, i'm using this script

 using UnityEngine;
 
 public class HealthScript : MonoBehaviour
 {
     
     public int hp = 1;
     private GUIText scoreReference;
 
     
     public bool isEnemy = true;
     
     
     public void Damage(int damageCount)
     {
         hp -= damageCount;
         
         if (hp <= 0)
         {
             // Dead!
             Destroy(gameObject);
             scoreReference.text = (int.Parse(scoreReference.text) + 1).ToString();
 
         }
     }
 
     void Start()
     {
         scoreReference = GameObject.Find("Score").guiText;
     }

i got some idea to retrieve the value of the score, but it won't display. Please help me.. Thanks