Considering most people have at least Full HD 1080p monitors these days, it’d appear as if macOS is running in a small window. If you have any questions about how to display Windows in full screen on VirtualBox or anything else, you can contact me here.When you use VirtualBox to run macOS in a guest environment, the default resolution for the operating system is set to 1024×768. You can switch from Windows to Mac and vice versa by swiping left / right on the trackpad. You are now displaying Windows in full screen on VirtualBox! Switching between Windows in full screen and Mac

You can check the new resolution by right clicking on your desktop and selecting Display settings and clicking on Advanced display settings at the bottom right: you will see that the new resolution is now selected there. It will take a few seconds to have the Windows resolution adjusted automatically. Once your Windows machine has been restarted, the Windows resolution will be automatically adjusted to your computer resolution (in my case my Mac). Then click Install one more time and click Finish to Reboot now. This will install all the drivers needed to display Windows in full screen. This will load the drivers on the CD drive of your virtual machine and then display a popup. Then click on Devices -> Insert Guest Additions CD image.

To do this, move your mouse to the top of the screen to display the menu. To fix the “black bars” issue and the screen being cut off, you need to install the VirtualBox Guest Additions. Installing the VirtualBox Guest Additions If you change the resolution to have it full screen you will still be missing some part of the screen. When you use the Windows in full screen on VirtualBox, it is still not full screen (you have black bars on the side). Issue with Windows in full screen on VirtualBox If you are not familiar with this process, I have a detailed post here on how to do it. To display Windows in full screen on VirtualBox, you will first need to install Windows on a virtual machine using VirtualBox.

Virtualbox full screen mode