1. Select the Design tool from the gray navigation bar.
2. If not already selected, select the Sitewide tab on the righthand sidebar.
3. Then, select Navigation.
In the screenshot below, you will see that there are two tabs to choose from, Desktop or Mobile. Desktop is chosen by default.
4. Select the Mobile tab to view your mobile navigation design settings.
5. In the Layout panel, you will see the Use mobile navigation on all devices tick box, enable the option here.
Note: Use of mobile navigation on the desktop view is currently only available on two layout types: Top Navigation (Logo Above) and Top Navigation (Logo Below).
6. Select Save and Publish to make your change live now.