[Theme Horse Support Team]

Hi Edwin,

To change the go to top button color you have to change the background image in style.css file.
We have used image on it not a color. To change the background image Go to Appearance -> Theme Options -> Design Options Tab -> Custom CSS paste the following CSS code and Click on save all changes button:

.back-to-top a {
    background-image: url("your-image-url");
}

*Change above text your-image-url to your image url.

Thank you!