There isn't a template page for small screens. The way that the page layout changes for small screens is controlled by the stylesheet. In your theme, this file is called style.css.
The stylesheet contains lots of styles that apply to all display sizes. Towards the bottom of the stylesheet there are a series of sections each starting with @media and some condition that states the display width that applies to the section.
Editing several styles for different display widths would take many hours and is above what can be achieved in a forum. So if you don't like how your theme looks on small screens you can:
- read a lot!
- hire someone
- or try some other themes. Look for one that features woo-commerce compatibility and a responsive design.