How to change importing settings of already imported models?

Hello,

I am trying to optimize my game. For that purpose I decided to play around with model importer settings. But I dont want to manually reimport all assets that I want to change for applying new settings. So I found OnPostprocessAllAssets method which loops all moved files. With that function I can apply all my settings with just moving root folder of my models.

Here is my code:

 public class BuildingImporter : AssetPostprocessor
 {
 
     static string folder = "Assets/Models(blend)/Yapılar/";
 
     // Use this for initialization
     void Start () {
     
     }
 
     static void OnPostprocessAllAssets(string[] importedAssets, string[] deletedAssets, string[] movedAssets, string[] movedFromAssetPaths)
     {
 
         //Loop in every moved asset and if directory is under of folder then goes into if condition
         for (int i = 0; i < movedAssets.Length; i++)
         {
 
             if (movedAssets[i].Length > folder.Length && System.String.Compare(movedAssets[i].Substring(0, folder.Length), folder) == 0)
             {
 
                 Debug.Log(movedAssets[i] + "is reimported");
 
                 ModelImporter importer=null;
 
                 try
                 {
                     //Get modelImporter
                     importer = (ModelImporter)AssetImporter.GetAtPath(movedAssets[i]);
                 }
                 catch (System.InvalidCastException e)
                 {
                     Debug.Log(movedAssets[i] + " doesnt have model importer");
                     return;
                 }
 
                 Debug.Log("compressed");
 
                 importer.meshCompression = ModelImporterMeshCompression.High;
 
                 
 
             }
         }
     }
 
    

However in that code asset importer cant be cast to model importer. So nothing happens to models after I move the folder.

Also if you have another approach for my purpose I would like to hear that. Thanks :)