I found the solution to hiding the button on mobile. You have to code several scroll buttons in the CSS Editor, for different configurations as follows:
@media only screen and (max-width:3000px) {
.scrollup {
width: 60px;
height: 40px;
position: fixed;
bottom: 50px;
right: 100px;
display: none;
}
}
And then add these next two, but leave the brackets inside blank:
@media only screen and (max-width:480px) {}
This one works for slightly smaller screens like tablets or when the phone is landscape:
@media only screen and (max-width: 1000px) {}