Hi there!
Thanks for your query.
Actually if any image used as background then it will not show fully on all devices, and it's normal.
However, you can use the following code in your custom CSS to get a better result:
.sp-slider .sp-item .sp-background {
background-position: 100% 100%;
background-repeat: no-repeat;
background-size: cover;
}
Note: Path towards custom CSS: Extensions>Templates>Styles> Click on your current default template name then choose Template Options. Then find custom CSS within the custom code.
Let me know your feedback:)
Best Regards