Hello,

Thank you very much for choosing our theme and for contacting us.

Please add this code to the Theme Settings > Custom CSS > Global:

@media(max-width: 768px) {
body .product-grid-item.col-6{
    -ms-flex: 0 0 33.333333%;
    flex: 0 0 33.333333%;
    max-width: 33.333333%;
}
}

Best Regards