Unityの２DゲームのButtonの設定について『初心者』

画像のところでPushButtonleftが選択できるようになるはずなのですが、候補に出て来ません、改善点などお教えして頂けると幸いです。質問があれば何でもお答えします。

C#
1using System.Collections;
2using System.Collections.Generic;
3using UnityEngine;
4
5public class GameManager : MonoBehaviour
6{
7    public const int WALL_FRONT = 1;
8    public const int WALL_RIGHT = 2;
9    public const int WALL_BACK = 3;
10    public const int WALL_LEFT = 4;
11
12    public GameObject panelWalls;
13
14    private int wallNO;
15    // Start is called before the first frame update
16    void Start()
17    {
18        wallNO = WALL_FRONT;
19    }
20
21    // Update is called once per frame
22    void Update()
23    {
24        public void PushButtonRight()
25        {
26            wallNO++;
27
28            if (wallNO > WALL_LEFT)
29            {
30                wallNO = WALL_FRONT;
31            }
32            DisplayWall();
33        }
34        public void PushButtonLeft()
35        {
36            wallNO--;
37
38            if (wallNO > WALL_FRONT)
39            {
40                wallNO = WALL_LEFT;
41            }
42            DisplayWall();
43        }
44        void DisplayWall()
45        {
46            switch (wallNO)
47            {
48                case WALL_FRONT:
49                    panelWalls.transform.localPosition = new Vector3(0.0f, 0.0f, 0.0f);
50                    break;
51
52                case WALL_RIGHT:
53                    panelWalls.transform.localPosition = new Vector3(-1000.0f, 0.0f, 0.0f);
54                    break;
55
56                case WALL_BACK:
57                    panelWalls.transform.localPosition = new Vector3(-2000.0f, 0.0f, 0.0f);
58                    break;
59
60                case WALL_LEFT:
61                    panelWalls.transform.localPosition = new Vector3(-3000.0f, 0.0f, 0.0f);
62                    break;
63            }
64        }
65    }
66}
67