"Some values driven by Slider" - How to force slider to respect my changes?

When creating a Slider in 4.6+'s UI system, a compound object is created:

—fill area
—handle slide area

I am attempting to change the “left” and “right” properties of the “fill” object’s RectTransform, such that when the slider’s value is zero, there is absolutely no fill, and when the value is 1, the entire background is covered. Setting the “left” and “right” to zero seems to accomplish this at first glance. However, when I enter play mode, the “left” and “right” values I’ve chosen are reverted to their defaults (-5).

After chasing my tail thinking this was an issue related to the compound slider objects being prefab instances, I have come to believe this isn’t the case. How can I force Unity to respect the changes I’m making to these RectTransforms? I am warned in the inspector for this RectTransform that “Some values driven by Slider” - so how can I circumvent this?

Big thanks,

Yes,I found out how to slove this.Set the Image’s anchor stretch in two directions which in Fill Rect property in slider component.

@suhao123 you need to elaborate on that. I would also like an answer to this please.

Also let me know @AlwaysSunny if you found how to fix it

@AlwaysSunny let me know if you found an answer to this

Ok so what Suhao means is:

On the box-looking positioning tool, the anchor presets,
You have to set it to Stretch Stretch.

Hopefully this makes sense! @AlwaysSunny