Apply gravity to my character through script.

Hi Im trying to apply gravity to my character because when he jumps you comes down really slowly its like he's on the moon. Ive tried everything I can but I cant get him to come down faster when he jumps. This is a platforming game so its like he can jump over 2 Platforms when you press Space.

Heres my script so far:

 using UnityEngine;
 
 public class Runner : MonoBehaviour 
 {
     public static float distanceTraveled;
     
     public float acceleration;
     
     private bool touchingPlatform;
     
     public Vector3 jumpVelocity;
     
     public Vector3 Gravity;
     
     public float gameOverY;
 
     void Update () 
     {
         if(touchingPlatform && Input.GetButtonDown("Jump"))
         {
             rigidbody.AddForce(jumpVelocity, ForceMode.VelocityChange);
             rigidbody.AddForce(Gravity, ForceMode.VelocityChange);
             touchingPlatform = false;
         }
         
         distanceTraveled = transform.localPosition.x;
         
         if(transform.localPosition.y < gameOverY)
         {
             Application.LoadLevel("GameOver");
             
         }
     }
     
     void FixedUpdate()
     {
         if(touchingPlatform)
         {
             rigidbody.AddForce(acceleration, 0f, 0f, ForceMode.Acceleration);
         }
     }
     
     void OnCollisionEnter()
     {
         touchingPlatform = true;
     }
     
     void OnCollisionExit()
     {
         touchingPlatform = false;
     }
     
 }

Thanks in advance.