How to get Update to acknowledge variable value from other method

So I'm trying to write a script in Unity where, when right clicking while the mouse is being followed (I changed it so the cursor is replaced instead, but that's off-topic), that the cursor will change again to a specific texture.

However, for this to work, I need the "color value" variable to have a specific value... but it keeps returning as null in the Update method. Any help on how to get Update to know what the current crayonValue is?

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

public class ColoringScript : MonoBehaviour
{
    // Variables
    public GameObject brownCrayon;
    public GameObject selectedShape;
    public Sprite uncolored;
    public Sprite colored;
    public Texture2D brownUnflipped;
    public Texture2D brownFlipped;
    public CursorMode cursorMode = CursorMode.ForceSoftware;
    private GameObject activeCrayon;
    private string crayonValue;
    private string activeTag;
    private bool isFollowingMouse = false;
    private bool isFlipped = false;
    private Vector2 startPos;
    private Vector2 pos;
    private Vector2 movePos;
    private Vector2 hotSpot = Vector2.zero;
    private Image activeImage;
    private Texture2D cursorTexture;

    void Update()
    {
        if(isFollowingMouse)
        {
            if(Input.GetMouseButtonDown(1))
            {
                Debug.Log(crayonValue);
                WasFlipped(crayonValue); // Calls the WasFlipped function to flip the crayon
            }
            if(Input.GetMouseButtonDown(0))
            {
                isFollowingMouse = false; // Sets the boolean so the object stop following the mouse
                activeImage.enabled = true; // Makes the current crayon visible again
                activeCrayon = null; // Empties the activeCrayon variable
                activeImage = null; // Empties the activeRenderer variable
                activeTag = null; // Empties the activeTag variable
                crayonValue = null; // Empties the craonValue variable
                cursorTexture = null; // Reverts the cursor texture
                Cursor.SetCursor(cursorTexture, hotSpot, cursorMode); // Returns the cursor to its default state
            }
        }
    }

    // WasClicked is called when a crayon is left-clicked
    public void WasClicked(string crayonValue)
    {
        switch(crayonValue)
        {
            case "brown":
                activeCrayon = brownCrayon; // Sets the activeCrayon variable to the brown crayon
                activeImage = activeCrayon.GetComponent<Image>(); // Sets the activeRenderer variable
                activeImage.enabled = false; // Makes the crayon invisible
                activeTag = "brown"; // Sets the variable activeTag for ease when clicking a shape
                cursorTexture = brownUnflipped; // Sets the cursorTexture value to the brown crayon default side
                break;
        }
        isFollowingMouse = true; // Sets the boolean so the code knows the cursor is being followed
        Cursor.SetCursor(cursorTexture, hotSpot, cursorMode); // Changes the cursor to simulate picking up the crayon
    }

    // WasFlipped is called when an active crayon is right-clicked
    public void WasFlipped(string crayonValue)
    {
        switch(crayonValue)
        {
            case "brown":
                if(!isFlipped)
                {
                    Debug.Log("flipped brown");
                    isFlipped = true; // States that the crayon is currently flipped
                    cursorTexture = brownFlipped; // Flips the crayon by changing the cursor
                }
                if(isFlipped)
                {
                    isFlipped = false; // States that the crayon is currently being flipped back to normal
                    cursorTexture = brownUnflipped; // Flips the crayon back to its original side
                }
                break;
        }
        Cursor.SetCursor(cursorTexture, hotSpot, cursorMode); // Changes the cursor to simulate flipping the crayon
    }

    // WasColored is called when a shape is clicked
    public void WasColored()
    {
        Debug.Log("Colored" + crayonValue);
        selectedShape.tag = activeTag; // Sets the tag of the shape to the currently active tag
        selectedShape.GetComponent<Image>().sprite = colored; // Colors the shape by changing the source image
    }
}