Unity UI Buttons don't work with Input.GetAxisRaw("Horizontal")

I have a really strange problem. A month ago I was playing with this small game and after successfully making the controls I left it. Now I came back to finish it up, but it turns out my last progress wasn't saved. Now I can't remember how I transformed my controls form the arrow key to UI_buttons on the screen. The only buttons I had were Left and Right. Here is the code from my Update, which shows the code that allows me to move the player with the arrow keys:

  void Update () {
         float inputX = Input.GetAxisRaw("Horizontal");
         float velocity = inputX * speed;
         transform.Translate(Vector2.right * velocity * Time.deltaTime);
 
         if (transform.position.x < -screenHalfWidthInWorldUnits)
         {
             transform.position = new Vector2 (screenHalfWidthInWorldUnits, transform.position.y);
 
         }
 
 
         if (transform.position.x > screenHalfWidthInWorldUnits)
         {
             transform.position = new Vector2(-screenHalfWidthInWorldUnits, transform.position.y);
 
         }
     }

My variables and Start:

 public float speed = 7;
 public event System.Action OnPlayerDeath;
 float screenHalfWidthInWorldUnits;
 
 void Start () {
     float halfPlayerWidth = transform.localScale.x / 2f;
     screenHalfWidthInWorldUnits = Camera.main.aspect * Camera.main.orthographicSize;
     FindObjectOfType<AudioManager>().Play("engine");
 }

What I want, but can't seem to do. I have two UI buttons which have Pointer Down and Pointer Up events. I want to just use the code above and make the player move left or right, similar to the arrow keys. This is what I thought my last code was, but it didn't work. Not even close. I do remember it was really short. A line or two at the most.

 public void MoveRight() // PointerDown for Right button
     {
     }
 
     public void MoveLeft() // PointerDown for Left button
     {
     }
 
     public void Stop() // PointerUp for stop movement.
     {
     }

Any help is much appreciated! Thank you!