Changing scroll bar style does not effect its height xml java android studio

Question

I am trying to change the style of Scrollbar of a GridView. The new style I created is applied successfully but unfortunately the length and width of scroll bar still remains default. How do I change them.

This is my custom_scroll_bar_thumb.xml inside my drawable folder:

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:aapt="http://schemas.android.com/aapt">
    <item>
        <shape android:shape="rectangle">
            <solid android:color="#0288d1"/>
            <size android:height="10dp" android:width="5dp"/>
            <corners android:radius="10dp"/>
        </shape>
    </item>
    <item android:gravity="center_vertical|center_horizontal|center|clip_vertical" android:height="4dp" android:width="4dp" android:drawable="@drawable/up_and_down" android:top="2dp" android:bottom="2dp"/>
</layer-list>

As you can see I have defined its height and width here. But it does not seem to take any effect.

After this I created a style named custom_scroll_bar in my styles.xml, like this:

<style name="custom_scroll_bar">
        <item name="android:scrollbarAlwaysDrawVerticalTrack">true</item>
        <item name="android:scrollbarStyle">outsideOverlay</item>
        <item name="android:scrollbars">vertical</item>
        <item name="android:fadeScrollbars">false</item>
        <item name="android:scrollbarThumbVertical">@drawable/custom_scroll_bar_thumb</item>
    </style>

Now I have used it inside my grid view like with

style="@style/custom_scroll_bar"

This is my grid view:

                <GridView
                    android:id="@+id/galleryViewGridView"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:paddingStart="5dp"
                    android:paddingTop="5dp"
                    android:paddingBottom="5dp"
                    android:paddingEnd="5dp"
                    android:numColumns="3"
                    android:horizontalSpacing="8dp"
                    android:verticalSpacing="8dp"
                    style="@style/custom_scroll_bar"
                    android:stretchMode="columnWidth">
                </GridView>

This is the output I am getting:

As you can see the scroll bar still has default height and width. How can I change that. Thank you.