Hi, you have to add css for the custom logo into the theme files. If the code is not present it uses the default from the plugin.
Add to the style.css file that you are using (style1.css for example):#rt-logo {
background: url(....Your URL HERE) 0 0 no-repeat;
width: 185px;
height: 115px;
}
Change the URL to your image path and change the width and height to match your image.