The Navigation Menu is placed under the Build section of your app. It allows you to manage the colours of the Top Bar and the Navigation Bar of your app.
The Design section allows you to choose the colours and to show/hide the share button for your app.
The Layout section allows you to choose the style of your Menu Layout of your app.
You can choose between the Drawer Menu and the Bottom Tabs Menu.
Under Drawer menu layout, you have an option to align the text of the menu to the left or center.
Please Publish your app once you have made the changes, so they get reflected on your mobile app successfully.