Hi there,
1. Show navigation on scroll
i) Enable the Navigation as Header in Customizer > Layout Header.
ii) Set your Navigation background color in Customizer > Colors
iii) Enable the Sticky Navigation in Customizer > Layout > Sticky Navigation
iv) Add this CSS to your Customizer > Additional CSS:
#site-navigation:not(.is_stuck) {
display: none;
}
2. Back to Top button you can enable in Customizer > Layout > Footer
Let me know if i understood correctly 🙂