You can see a working demo of the back to top module on this page. The one configurable option for this module is the trigger point. By default, the button shows once user has scrolled past 65% down the page. You can adjust the trigger point by updating the attribute data-trigger-value=""
on .amnh-back-to-top
.
* This is our default value, used as an example here. This would be whatever value you set as described above. ** This is a set value. Is always the same across any page, independtly of trigger point value, can only be modified in code.