The option you're looking for can be found by navigating to Shopkeeper > Customize > Header Layout & Style > Sticky Header:
Articles in this section
- How to upload my logo?
- Change the Address Bar Icon/Favicon
- How to work with Header Transparency?
- Navigation — How to add links to product categories?
- Navigation — Multi-column drop-down menus
- Navigation — Call-to-action buttons
- How to change the header layout?
- How to enable sticky header (keep header on screen)?