*SOLVED* How do I make the player jump at a fixed speed?

Hi, I am making a 2D game using the UI canvas system and I ran into a problem with the height the player jumps to, and the speed of the game overall. When I play the game in the editor on small screen, the player jumps higher, and the platform moves faster, then when I maximise on play the platform moves slower and the player jumps a lot lower. I have also built it through Xcode and tested on my iPad which also gives me a different result from the other 2. Is there any way that I can make the jump height constant, as well as the speed of the game overall? I have looked at lots of answers already but not of them have solved my issue. Below are my scripts for the player jumping and the platform movement. Thanks

Player jumping:

var myRigidbody : Rigidbody2D;
var _jumpSpeed = 1500.0f;
var grounded : boolean = false;
var groundCheck : Transform;
var groundRadius : float = 0.2f;
var whatIsGround : LayerMask;

function Start(){
	myRigidbody = transform.gameObject.GetComponent(Rigidbody2D);
}

function FixedUpdate(){

	grounded = Physics2D.OverlapCircle(groundCheck.position, groundRadius, whatIsGround);

	if(grounded){

			if(Input.GetMouseButtonDown(0))

			myRigidbody.AddForce(new Vector2(0, _jumpSpeed * Time.fixedDeltaTime));

		}
	}

Platform movement:

var platformSpeed : float = 300.0f; 
var beginLevel : boolean;

function Update(){
if(Input.GetMouseButtonDown(0))
	beginLevel = true;
if(beginLevel)
	transform.Translate(Vector3.right * Time.deltaTime * -platformSpeed);
}

It turned out that the problem was the fact that on the canvas, the render mode was set to “Screen Space - Overlay”, but when I changed it to “Screen Space - Camera” and selected the main camera in the scene it worked fine.