How to make highscore work on android? highscore restarts on game restart

Hey! So I am trying to make a clone of flappy bird and of course there has to be highscore…and my highscore is working on computer but not on android phone…Yes I am pretty new to unity I’ve been working with it for like 4 days.

EDIT: seems like I have messed something up since it is not working on computer anymore either…
EDIT 2: got it working on computer and android phone but the highscore restarts on restart…any ideas?

Here is my code:

using UnityEngine;
using System.Collections;

public class Score : MonoBehaviour {

static int score = 0;
static int Highscore = 0;

static public void AddPoint() {
	score++;

	if (score > Highscore) {
		Highscore = score;	
	}
}

void Start(){
			score = 0;
			Highscore = PlayerPrefs.GetInt ("Highscore", 0);
	}

void OnDestroy() {
	PlayerPrefs.SetInt ("Highscore", Highscore);
}

void Update() {
	guiText.text = "Score: " + score + "

High Score: " + Highscore;
}

}

Are you sure OnDestroy gets called? Try moving the writing to prefs into AddPoint() ?

if (score > Highscore) {
         Highscore = score;
         PlayerPrefs.SetInt ("Highscore", Highscore);

     }