Script doesn't affect rigidbody's values.

I have a script that rotates the box with addTorque. The script works fine, but the box feels "slidely" over the addTorque, so I added some if statements that whenever the player input is 0, the angular drag increases, but the angular drag doesn't change in any way.

Here's the script

 using UnityEngine;
 using System.Collections;
 
 public class Rigidbody_Controls : MonoBehaviour {
 
     public float amount;
     private Rigidbody boxRigidbody;
     private float h;
     private float v;
     private float rigidbodyDefaultAngularDrag;
 
     void Start()
     {
         boxRigidbody = GetComponent<Rigidbody>();
         rigidbodyDefaultAngularDrag = boxRigidbody.angularDrag;
     }
 
     void Update()
     {
         h = Input.GetAxis("Horizontal") * amount * Time.deltaTime;
         v = Input.GetAxis("Vertical") * amount * Time.deltaTime; 
 
         Debug.Log(h);
 
         boxRigidbody.isKinematic = false;
         boxRigidbody.useGravity = false;
         boxRigidbody.AddTorque(Vector3.up * h);
         boxRigidbody.AddTorque(Vector3.left * v);
 
         if(h == 0)
         {
             boxRigidbody.angularDrag = 1 * Time.deltaTime;
         }
 
         if(boxRigidbody.velocity.magnitude < .9)
         {
             boxRigidbody.angularDrag = rigidbodyDefaultAngularDrag;
         }
     }
 
 }