Unity: Attaching a volume control slider that doesn't always exist, to another object.

Hello everyone, I am really new to Unity and have been trying to create a small game. In this game there is an options menu, which contains two sliders, one for the background music volume, and one for the SFX volume. I created the options menu within it's own scene, and have a persistent empty object which plays the game's music. The music player uses this simple C# script:

 using UnityEngine;
 using System.Collections;
 using UnityEngine.UI;
 
 public class musicVolume : MonoBehaviour
 {
     public Slider musicControlSlider;
     public AudioSource backgroundMusic;
     void Start()
     {
         backgroundMusic.Play();
 
     }
 
     void Update()
     {
 
         {
             backgroundMusic.volume = musicControlSlider.value;
 
         }
     }
 }

While this does successfully keep the music playing at whatever the user set in the options menu with the slider, I noticed a couple serious issues, and have been unable to resolve them.

Firstly, when I change scenes the music control slider is set to missing, as one would expect, however if I return to the options menu, the slider becomes set to "None" rather than what I graphically set it to (MusicSlider (Slider)).

Secondly, I am unable to graphically reset the slider while play mode is enabled in the editor.

Is there any way to detect the musicslider (MusicSlider), which is a child of optionsMenu, Canvas, optionsManager in the scene options whenever musicprefab (the background music object) enters the scene? That is I want this to happen whenever musicprefab enters the scene

Rather than this

Thank you.