Firstly, you will require Custom Marker Add-on
Then, you can edit, admin/includes/validate.php
Search and change the value below:
$marker_resize_image_width = 30;
Next, edit js/super-store-finder.js or js/super-store-finder-mobile.js and search/modify code below:
if(v.cat_marker_img!=''){ var image = new google.maps.MarkerImage( v.cat_marker_img, new google.maps.Size(34,46), new google.maps.Point(0,0), new google.maps.Point(17,46)); } else { var image = new google.maps.MarkerImage( 'img/image.png', new google.maps.Size(34,46), new google.maps.Point(0,0), new google.maps.Point(17,46) ); }
Finally, clear cache and reupload the markers via admin.
* Take note, coding knowledge may be required to perform changes above.