How to change aim from script?

How do I assign new values or access existing values of the freelook camera rigs from script? I've included an image with the variables I'd like to change.

Edit: I've managed to add an offset by using CinemachineCameraOffset. Although I've created the behavior that I needed I'd still appreciate an answer on how to access those variables.

 

Thanks

 

What am I doing wrong? when I press the button it crashes and shows this:

NullReferenceException: Object reference not set to an instance of an object

cameraController.Update () (at Assets/cameraController.cs:20)

This is the script

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using Cinemachine;
5.  
6. public class cameraController : MonoBehaviour
7. {
8.     public CinemachineVirtualCamera vcam;
9.     // Start is called before the first frame update
10.     void Start()
11.     {
12.      
13.     }
14.  
15.     // Update is called once per frame
16.     void Update()
17.     {
18.         if(Input.GetButton("Move"))
19.             {
20.             vcam.GetCinemachineComponent<CinemachineComposer>().m_ScreenX = 100f;
21.             }
22.         }
23. }
24.  

The script is in the CM FreeLook1 object.

Thank you for the help