ThemesWP

Using Ultimate Custom ScrollBar for customize scrollbars, you get a very elegant and unique site. Consistent scroll behavior for every device. You can change scrollbar size, colors, animation, position from this settings page.
Plugin Features
<ul>
<li>Simple installation & activation</li>
<li>Supported touch devices.</li>
<li>Unlimited colors.</li>
<li>Lightweight.</li>
<li>Enable/Disable Option.</li>
<li>Easy Option Panel.</li>
<li>All browser supported</li>
</ul>
Free Options
<ul>
<li>Enable/Disable ScrollBar : You can enable or disable scrollbar using this option.</li>
<li>Cursor Width : You can increase or decrease cursor width using this option.</li>
<li>Rail Background Color : You can change rail background color from this color picker.</li>
<li>Cursor Color : You can change cursor color from this color picker.</li>
<li>Auto Hide Mode : You can select scrollbar auto hide mode from this selectbox.</li>
<li>Included all free options.</li>
<li>Cursor Border : You can control cursor border using this option.</li>
<li>Cursor Border Radius : You can control cursor border radius using this option.</li>
<li>Scroll Speed : You can control scroll speed using this option.</li>
<li>Mouse Scroll Step : You can control mouse scroll step using this option.</li>
<li>Emulate Touch : Enable cursor-drag scrolling like touch devices in desktop computer.</li>
<li>Minimum Cursor Height : You can set the minimum cursor height.</li>
<li>Bounce Scroll : Enable scroll bouncing at the end of content as mobile-like.</li>
<li>Horizrail Enabled : You can control horizontal scroll.</li>
<li>Rail Align : You can control alignment of vertical rail.</li>
<li>Rail Valign : You can control alignment of horizontal rail.</li>
<li>Enable Mousewheel : You can control Mousewheel using this option.</li>
<li>Enable Keyboard : You can enable or disable keyboard events using this option.</li>
<li>Hide Cursor Delay : You can set the delay in microseconds to fading out scrollbars.</li>
<li>Enable Scroll On Selection : You can enable auto-scrolling of content when selection text.</li>
<li>Cursor Drag Speed : You can set speed of selection when dragged with cursor.</li>
</ul>

Ultimate Custom ScrollBar

Using Ultimate Custom ScrollBar for customize scrollbars, you get a very elegant and unique site. Consistent scroll behavior for every device.

Themepoints

Scrollbar wp is fully customizable WordPress scrollbar plugin. You can change scrollbar color, border radius, scroll speed, width, border style & other settings using plugin option page.
<h3>Scrollbar by https://themepoints.com</h3>
<ul>
<li><a href="https://themepoints.com" rel="nofollow ugc">Live demo!»</a></li>
</ul>
Plugin Features 
<ul>
<li>Simple installation & activation</li>
<li>Unlimited colors.</li>
<li>CSS3 animation.</li>
<li>Supported touch devices.</li>
<li>All browser supported</li>
<li>Custom Width.</li>
<li>Scrollbar border radius.</li>
<li>Scrollbar scroll speed.</li>
<li>Scrollbar border.</li>
<li>Auto Hide Mode Enable/Disable.</li>
<li>Lightweight.</li>
<li>Easy Option Panel.</li>
<li>Easy Documentation.</li>
</ul>

Scrollbar

Customize your browser scrollbars with unlimited styling and color using scrollbar wp plugin.

Ultimate Custom ScrollBar vs Scrollbar