How to handle a Microsoft Controller? C#

Hey,

I have two more or less identical characters in my scene. I can switch between them with...

     private GameObject Character1;
     private GameObject Character2;
 
     void Start () {
         Character1 = GameObject.Find("Character1");
         Character2 = GameObject.Find("Character2");
 
         Character1.SetActive (true);
         Character2.SetActive(false);
 
     }
     
     void Update()
     {
         if (Input.GetKeyDown (KeyCode.Mouse0)) {
             Character2.SetActive(true);
             Character1.SetActive(false);
         }
 
         if (Input.GetKeyDown (KeyCode.Mouse1)) {
             Character2.SetActive(false);
             Character1.SetActive(true);
         }
     }
 }

Everything worked fine and I could control both characters with the keyboard. But then I connected a Microsoft Controller. Without doing anything I can control Character1 but when I switch to Character2 I can’t control him.

The Problem is: I don´t know why I’m able to control Character1 with the MS Controller in the first place.

Any idea what happened and why I can control one but not the other?