Build resolution errors

I watched the video of the "Brackeys" to make the "options" menu, it happens that when I do the build, every time I open the game it appears with a giant resolution and even if it changes it is still giant, with the buttons and texts are always the same size Code:

private void Start() { resolutions=Screen.resolutions;

     resolutionDropdown.ClearOptions();
     List<string> options = new List<string>();

     int currentResolutionIndex = 0;

     for(int i=0;i<resolutions.Length;i++)
     {
         string option = resolutions[i].width + "x" + resolutions[i].height;
         options.Add(option);

          if(resolutions[i].width==Screen.currentResolution.width && resolutions[i].height==Screen.currentResolution.height)
         {
             currentResolutionIndex = i;
         }
     }

     resolutionDropdown.AddOptions(options);
     resolutionDropdown.value = currentResolutionIndex;
     resolutionDropdown.RefreshShownValue();

 }

 public void SetResolution(int resolutionIndex)
 {
     Resolution resolution = resolutions[resolutionIndex];
     Screen.SetResolution(resolution.width, resolution.height, Screen.fullScreen);
 }