How to Fix the iPhone Horizontal Screen in monaca

I use monaca's IDE to make simple games.
I'd like to set up a fixed horizontal screen, but as stated in the official document, edit the UISsupported Interface Orientations in Monaca-AppInfo.plist, and

<key>UISsupportedInterfaceOrients</key>
  <array>
    <string>UIInterfaceOrientationLandscapeRight</string>
  </array>

I did so.
The recognition is that by erasing the vertical line (→not allowed), the setting is only compatible with the horizontal screen, but it doesn't reflect when I preview or debug the actual machine.
I wonder if this has failed to be configured.
Or can't I check it without actually building it as an iOS app?