If the display does not have the right resolution, you have to change it on the box. Here is an explanation how to change it.

1. Stop the Kiosk Mode of the Chromes Box, see this article:
​http://help.hotel-mssngr.com/en/articles/3566685-how-to-stop-the-kiosk-mode

2. On the box, open the settings:

3. Select the settings:

4. The settings open as a website. Select "Device" and "Display":

5. Adjust the resolution of the device as needed: