Getting wrong value of variable

HEY, HOW’S IT GOING, BUDDYS?

I need some your help today. All in all, I have 3 main scripts: globalvariables.cs (where I save all my global variables), onTreeClicked.cs (event when I click on button) and CoinExchange.cs (also event when I click on button). All other scripts doesn’t really have a matter.

I’ll try explain what they do. In my first script (globalvariables.cs) I save all my global varibles:

globalvaribles.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

public class globalvariables : MonoBehaviour {
    public int Wood;                // Creating a Wood variable
    public int Coin;                // Creating a Coin variable
}

Then I take them to my second script (onTreeClicked.cs). I’mma left screenshot with comments what every line do.
I add 1 to Wood a click. And as I can understand it changes it’s value from default. (in my globalvariables I dont say that Wood = 0 or smth. So I reckon that when I add 5 to Wood it equals 5.)

onTreeClicked.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

public class onTreeClicked : globalvariables {          // Getting all variables from globalvariables script

    private Shake shake;                    // Variable for Camera Shaking
    private Hit hit;                        // Varible for hit
    private ParticleSystem woodeffect;      // Wood icon appears above the tree
    private ParticleSystem pluseffect;      // 'plus effect' next to wood icon
    private Text woodcount;                 // Wood count text
    private Text coincount;                 // Coin count text

    void Start () {
        shake = GameObject.FindGameObjectWithTag("ScreenShake").GetComponent<Shake>();                      // Getting Components//
        hit = GameObject.FindGameObjectWithTag("Player").GetComponent<Hit>();                               //*******************//
        woodeffect = GameObject.FindGameObjectWithTag("woodeffect").GetComponent<ParticleSystem>();         //*******************//
        pluseffect = GameObject.FindGameObjectWithTag("pluseffect").GetComponent<ParticleSystem>();         //*******************//
        woodcount = GameObject.FindGameObjectWithTag("woodcount").GetComponent<Text>();                     //*******************//
        coincount = GameObject.FindGameObjectWithTag("coincount").GetComponent<Text>();                     // Getting Components//


        woodcount.text = Wood.ToString();           // Display start Wood value
        coincount.text = Coin.ToString();           // Display start Coin value
        pluseffect.Stop();                          // Stoping plus effect
        woodeffect.Stop();                          // Stoping wood effect
        
    }


    public void OnButtonTapped()                    // onClick function
    {
        shake.camShake();                           // Shake animation activated
        hit.charHit();                              // Hit animation activated
        Wood++;                                     // Add 1 to Wood variable
        woodcount.text = Wood.ToString();           // Show new value of wood
        woodeffect.Play();                          // Playing wood effect
        pluseffect.Play();                          // Playing plus effect
        


    }



	void Update () {
        
    }
}

In my third script (CoinExchange) I wanna exchange wood for coins (1 coin = 5 wood). But when I tryna get Wood varible from onTreeClicked.cs (that must equal some value) I get 0. I mean, when I’m checking Wood variable it equals 0.

CoinExchange.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

public class CoinExchange : onTreeClicked {             // Getting variables from onTreeClicked.cs 

    private Text coincount;                 // Coin count text

    void Start (){
        coincount = GameObject.FindGameObjectWithTag("coincount").GetComponent<Text>();                     // Getting Components//
    }

	void Update (){
        
	}

    public void Exchange()                  // onClick event
    {
        Debug.Log(Wood);                    // Checking Wood value        
    }


}

**Guys, I'm asking for your help. Every answer will be appreciated.**

I have found solution. I only need to use static variable.