Hi Sarah-
This issue is due to the way that Safari on iOS handles the “Cover Page” image size together with the “Fixed” background position.
In order to fix it, navigate to Customize > Advanced > Custom JS & CSS and paste the following code into your Custom Theme CSS field:
@media only screen and (max-device-height : 1024px) and (max-device-width : 1024px) {
.palette-primary.custom-background, .boldgrid-section.background-fixed {
background-attachment: scroll !important;
background-position: center top !important;
}
}