Help! With player positions after scene change!!

Hello, I never post here but I've been stuck on the same damn problem for two days and I'm pulling my hair out!!

Basically, it has recently snowballed into two problems: 1) After I load the next scene (I'm testing it with 4 to 5) it doesn't update quickly enough or something as my if statement isn't triggering to set the position? 2) The latter half of the code is devoted to loading a menu scene (8) when the player presses 'e'. It does this, but I need the player to be in the same position when they come back!!! I've tried the dontdestroyonload thing and it worked but then it wouldn't set the corect position when I changed scenes normally (like, 4 to 5)!!!!

please help!!

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.SceneManagement;
 
 public class sceneManage : MonoBehaviour {
 
     //private string currentScene;
     private GameObject player;
     //private Vector3 playerPosition;
     private float x;
     private float y;
     private float z;
     private Vector3 posVec;
     //string X = "";
     //string Y = "";
     //string Z = "";
 
     void Start ()
     {
     player = GameObject.Find("userPlayer");
 
 
     }
 
     void Update ()
     {
         //sceneSwitch ();
         //player = GameObject.Find("userPlayer");
 
     }
 
     void OnTriggerEnter2D(Collider2D changeScene)
     {
             
         if (gameObject.tag == "levelForwardTransition") {
             SceneManager.LoadScene ((SceneManager.GetActiveScene ().buildIndex) + 1);
 
             if ((SceneManager.GetActiveScene ().buildIndex) == 5) {
                 player.transform.position = new Vector3 (-0.79f, -1.89f, 0f);
                 Debug.Log("pos ran");
             }
         }
 
         if (gameObject.tag == "levelBackTransition") {
             SceneManager.LoadScene ((SceneManager.GetActiveScene ().buildIndex) - 1);
             //currentScene = (SceneManager.GetActiveScene ().buildIndex);
             }
     }
 
         
     void sceneSwitch()
     {
         if (Input.GetKey (KeyCode.E)) {
             if (SceneManager.GetActiveScene ().buildIndex != 8) {
                 PlayerPrefs.SetString ("previousScene", SceneManager.GetActiveScene ().name);
                 x = player.transform.position.x;
                 PlayerPrefs.SetFloat("x", x);
                 y = player.transform.position.y;
                 PlayerPrefs.SetFloat("y", y);
                 z = player.transform.position.z;
                 PlayerPrefs.SetFloat("z", z);
                 SceneManager.LoadScene (8);
                 x = PlayerPrefs.GetFloat("x");
                 y = PlayerPrefs.GetFloat("y");
                 z = PlayerPrefs.GetFloat("z");
                 posVec = new Vector3(x,y,z);
                 Debug.Log (x);
                 Debug.Log (y);
                 Debug.Log (z);
                 Debug.Log (posVec);
                 Debug.Log ("yes save");
 
 
 
             } 
 
             if (SceneManager.GetActiveScene ().buildIndex == 8) {
                 string lastScene = PlayerPrefs.GetString ("previousScene");
                 SceneManager.LoadScene (lastScene);
                 SceneManager.LoadScene (lastScene);
                 Debug.Log ("yes change");
 
                 Debug.Log ("yes back");
             }
             positionn ();
         }
 
     }
 
     void positionn () {
         if (SceneManager.GetActiveScene ().buildIndex != 8) {
             player.transform.position = (posVec);
             Debug.Log ("yes position");
 
         }
     }
 
     void OnSceneLoded (){
         if ((SceneManager.GetActiveScene ().buildIndex) == 5) {
             player = GameObject.Find ("userPlayer");
             player.transform.position = new Vector3 (-0.79f, -1.89f, 0f);
             Debug.Log ("pos ran");
         }
 
     }
 
 
 
 
 }