A 'Scroll to Top' button can enhance usability of your website. There are several plugins available out there that can help you achieve this. You just need to install the plugin and activate it.
Few days back, I've written a plugin that adds this feature to a WP site. Unlike other similar plugins, this one contains 80 of built-in icons that you can choose from.
And of course, you can upload your own icon.
But what about the icon position?
Yes, this plugin will allow you to choose the position of your icon. You can set the icon at left or right, padding from sides as well as time to scroll to top etc.
You can download it from the official repository of WordPress.
And here is a sample output-