how to change a variable from? an object in this array with a gui.button

well I'm trying to make a rts and like any rts, when you select your "troops" they are shown in a window with your photos and hp ...

I managed, but it activates the bool of the first object it finds the object of inves array that pressed the gui

 public Texture boneco;
     private Interface _interface;
     private Inventory inventory;
     private Vector2 _initialPosition;
     private Vector2 _finalPosition;
     public Texture2D RectangleTexture;
     public static List<BaseUnit> _unitsInScene = new List<BaseUnit>();
     public Camera mainCamera;
     public BaseUnit[] _selectedUnits;
     public GameObject unidade;
     public bool showTroppsWindows = false;
     private Rect troppsRect = new Rect(0, 400, 300, 100);
 
     public Interface intface = new Interface();
 
     public bool mouseOverWindows = false;
 
     private Rect avatarRect = new Rect(0, 0, 25, 25);
     public int unitsX = 4;
     public int unitsY = 2;
     
     void Awake ()
     {
         _unitsInScene = new List<BaseUnit>();
         _selectedUnits = new BaseUnit[0];
         GameObject.FindGameObjectsWithTag("Player");
 
 
     }
     
     void Update ()
     {
 
     }
 
     void OnGUI () 
     {
 
         for(int i=0;i < _selectedUnits.Length;i++)  
         {
             if (GUI.Button(new Rect(10, 150 +(i * 50),50,50), boneco))
             {
                 _interface = GameObject.FindGameObjectWithTag("Player").GetComponent<Interface>();
                 _interface.interfacebox = !_interface.interfacebox;
                 Debug.Log("Show Interface of unit: " + i);
             }
         }