You would need to activate the module from Appearance >Nevo Options > Sticky Header.

After activating a module click on Customize > Header option to get started. Click to Sticky Header to open item settings.

Sticky Header Settings
- Sticky bar: Header Builder designed with 3 rows (Header Top, Header Main, Header Bottom), so you can set sticky for each row you want.
To enable sticky for header row, choose a header row and then check to option e.g Sticky Header main.
- Display: always sticky or sticky when rolled up.
- Sticky Logo & Sticky Logo retina: exclusively for sticky header.
- Logo Max Width:
- Styling: custom color, link color, background color, border color, border size.
- Sticky on Desktop or Mobile and custom height.