High score saving only once

I am trying to save the highscore of my player. Basically i made a platformer game like doodle jump and want to save the Highscore. The score works fine, its updates every frame and can increase & decrease. But my highscore is saving only once, i dont want that.
Please help me, i am newbie. This is not my script, i just changed a bit. (script from Brackeys tutorials)

Here is the Code

 using UnityEngine;
 using UnityEngine.UI;
 public class PlayerScore : MonoBehaviour
 {
     public Text score;
     public Text highscore;
     public Transform player;
 
 
     void Start()
     {
         highscore.text = PlayerPrefs.GetFloat("HighScore", 0).ToString("0");
     }
 
 
     void Update()
     {
         float number = player.position.y * 15;
         Debug.Log(number);
         score.text = "Score: " + number.ToString("0");
         if (number > PlayerPrefs.GetFloat("Highscore", 0))
         {
             PlayerPrefs.SetFloat("HighScore", number);
         }
 
 
     } 
 
 }

You are saving HighScore and looking for Highscore. They are not the same. Change it to;

          if (number > PlayerPrefs.GetFloat("HighScore", 0))
          {
              PlayerPrefs.SetFloat("HighScore", number);
          }

or Add a this to your global variables;

private const string HighScore = "HighScore";

and then do

SetFloat(HighScore, number);  

GetFloat(HighScore, 0);