How to set the scrolling position of a scroll bar?

I'm on Unity 5.2.3p3 and I want to reset the scrollrect/scrollbar position each time the user enables them.

Setting
UI.Scrollbar.value has no effect

 

I haven't used many scrollbars but I think they're linked to the scroll rect content position and size compared to the viewport size. So if you move the scroll rect content to the position you want, the scrollbar will adjust accordingly.

 

my problem is that the scroll rect content is changed at the same time

 

I am using this hope it helps.

using UnityEngine.UI;

// my unity Scrollbars name inside unity is Scrollbar
// variable for assigning GameObjects to
private GameObject thisGameObject;
// create variable to hold Script
private Scrollbar ScrollbarScript;

void Start()

{
// call function to find game object and script attached to it ( object name in unity, script name attached to object)
getGameObject("Scrollbar", "Scrollbar");
// call to set Scrollbar to top -- will change depending on scroll option (bottom to top or top to bottom) -- range 0.0 to 1.0
ScrollbarScript.value = 1f;
}

private Object getGameObject(string object, string objectClass)

{
// find GameObject
thisGameObject = GameObject.Find(object);

// conditional for items with different scripts -- could use switch statement
if (objectClass == "Scrollbar")

{
// find component Scrollbar (Script) of GameObject Scrollbar (unity GameObject)
ScrollbarScript = thisGameObject.GetComponent<Scrollbar>();

}
// returns GameObject -- this is not needed for this example, but might be useful
return thisObject;

}

 

using System.Collections;
using UnityEngine;
using UnityEngine.UI;
public class SRect : MonoBehaviour {

public ScrollRect _sRect;//
// Use this for initialization
void Start () {
StartCoroutine(SetValue());
}

IEnumerator SetValue()
{
yield return new WaitForEndOfFrame();
if (_sRect != null)
{
_sRect.verticalNormalizedPosition = 0.5f;//Range(0.0f,1.0f)
}
else
{
Debug.LogError("ScrollRect _sRect==NULL");
}

yield return null;
}
}

 

Setting UI.Scrollbar.value directly works for me (Unity 2018.4) however I have found it necessary under some scenarios to do this after waiting for the end of frame.

The wait is possibly required if the scrollbar is being enabled for the first time in the same frame the value is being set?