Can someone tell me how to make a projectile shoot at a Transform without moving to the Transform's new position?

So I have this script for enemies to shoot projectiles at the player and I want one to track the player as they move around and the others to just shoot to where the player was before they moved. Could someone tell me how I could make it so that if the plasma type is not 3, it moves to where the player was when the projectile was created?

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

public class Plasma : MonoBehaviour
{
    public int plasmaType;

    /* Plasma Types
     * 1 = Red - Explosive, Slow
     * 2 = Blue - Doesn't Track, Fast
     * 3 = Green - Tracks, Slow
    */

    public Transform target;
    private Transform stationaryTarget; //where the player was when the projectile was created (SHOULD NOT UPDATE)
    public float speed;

    void Start()
    {
        target = GameObject.FindGameObjectWithTag("Player").transform;
        stationaryTarget = target; //how can I make it so that this stays constant and doesn't update?
    }  

    void Update()
    {
        if (plasmaType != 3) //Doesn't track player
        {
            float step = speed * Time.deltaTime;
            transform.position = Vector3.MoveTowards(transform.position, stationaryTarget.position, step);
        }
        if (plasmaType == 3) //Tracks player
        {
            float step = speed * Time.deltaTime;
            transform.position = Vector3.MoveTowards(transform.position, target.position, step);
        }
    }

    public void OnCollisionEnter(Collision collision)
    {
        Destroy(gameObject); //Destroys the plasma if it collides with anything
    }
}

Thanks in advance

change the type of stationaryTarget to vector3 instead, and in Start() stationaryTarget = target.position and you move towards stationaryTarget.

Should give you exactly what you want i think.