Resolution settings not working in build mode, but working perfectly in editor

So I made a script for resolutions settings and it works perfectly in editor, but when i build it i have to press multiple times on the buttons to get to the next resolution.

Here is the code:

using System.Collections; using System.Collections.Generic; using UnityEngine; using UnityEngine.UI;

public class Resolutions : MonoBehaviour {

 public Text resText;

 private int resIndex = 0;
 private Resolution[] resolutions;

 // Use this for initialization
 void Start () {
     resolutions = Screen.resolutions;
     Screen.SetResolution(resolutions[resIndex].width, resolutions[resIndex].width, true);
 }
 
 // Update is called once per frame
 void Update () {
     resText.text = resolutions[resIndex].width + "x" + resolutions[resIndex].height;
 }

 public void PreviousResolution()
 {
     resIndex--;
     if(resIndex < 0)
     {
         resIndex = Screen.resolutions.Length - 1;
     }
 }

 public void NextResolution()
 {
     resIndex++;
     if(resIndex > Screen.resolutions.Length - 1)
     {
         resIndex = 0;
     }
 }

 public void OnMouseUp()
 {
     Screen.SetResolution(resolutions[resIndex].width, resolutions[resIndex].height, true);
 }

}

And here is how my options panel looks like: