Playerprefs across Scenes

Hello everyone, I am using playerprefs to save a single variable. I have several factors affecting this variable across several scenes. For instance, in scene a, script a is modifying the variable, but in scene b, script b is also modifying the variable. However, for some reason, the variable does not save between scenes. Does anyone have any troubleshooting advice? My scripts are below: (sorry for them being so long. I thought giving more info was better than giving less. If you need anything else, let me know.) using System.Collections;

 public class CarrotCount : MonoBehaviour 
 {
     public float x;
     public float y;
     public float z;
     public float unknown;
     public int carrotnumber;    // important
 
 
     void Start ()
     {
         StartCoroutine (fiveseconds ());
         carrotnumber = PlayerPrefs.GetInt ("carrotnumber", 10);
         Debug.Log (carrotnumber);
     }
 
 //    public void PLUS1 ()
 //    {
 //        Debug.Log ("Plus 1 carrot");
 //        carrotnumber += 1;
 //        Debug.Log (carrotnumber);
 //        PlayerPrefs.SetInt ("carrotnumber", carrotnumber);
 //
 //    }
     void OnGUI () {
         GUI.Box (new Rect (x, y, z, unknown), "Carrots:"+ carrotnumber);
     }
 
     void Update ()
     {
 
 //PlayerPrefs.SetInt ("carrotnumber", carrotnumber);
     //    carrotnumber = PlayerPrefs.GetInt ("carrotnumber");
     }
 
     IEnumerator fiveseconds ()
     {
         yield return new WaitForSeconds (1) ;
         PlayerPrefs.SetInt ("carrotnumber", carrotnumber);
         PlayerPrefs.Save ();
         Debug.Log (carrotnumber);
         StartCoroutine (fiveseconds ());
     }
     
 }

script a:

 using System;
 using UnityEngine;
 using UnityEngine.Advertisements;
 
 public class test1 : MonoBehaviour {
     public int xdist = 10;
     public int ydis = 10;
     public CarrotCount _carrotcount;
 
     void Awake() {
         if (Advertisement.isSupported) {
             Advertisement.Initialize ("64925");
         } else {
             Debug.Log("Platform not supported");
         }
     }
     
     void OnGUI() {
         if(GUI.Button(new Rect(xdist, ydis, 85, 40), Advertisement.IsReady() ? "Free Carrots" : "Waiting...")) {
             // Show with default zone, pause engine and print result to debug log
             Advertisement.Show(null, new ShowOptions {
                 resultCallback = result => {
                     Debug.Log(result.ToString());
                     _carrotcount.carrotnumber += 5;
                 }
             });
         }
     }
 }
 

script b:

 using UnityEngine;
 using System.Collections;
 
 public class Ifclicked : MonoBehaviour {
 
     public MoveCarrot _MoveCarrot;
     public CarrotCount _CarrotCount ;
     public string use;
     public killmole _killmole;
     GameObject carrotmaster;
 
     void Start ()
     {
 //        carrotmaster = GameObject.Find ("carrotmaster");
 //        CarrotCount _CarrotCount = (CarrotCount) carrotmaster.GetComponent (typeof(CarrotCount));
     }
     void OnMouseDown ()
     {
         
             _MoveCarrot.move ();
         _CarrotCount.carrotnumber += 1;
 
     }
 
 }

Once again, thank you for the help.