Changing the window resolution
You’ll notice that by default VirtualBox only displays at 800x600 resolution. But if you right click the Window in monitor icon at the bottom of the screen and select Virtual Screen 1, there are many more options available, but greyed out.
To resolve this we need to change some settings. Close the window and select Power off the machine.
Return to the manager window and select Settings.
Then navigate to the Display tab.
Change the Graphics Controller setting to VBoxSVGA and click OK (ignore the warning).
Now restart your virtual machine.
Once Ubuntu has started, you should now be able to select all of the available resolutions from the virtual monitor menu, or simply resize the window to adjust the display.
That’s the end of the primary tutorial. Congratulations, you now have Ubuntu running on a virtual machine!
What follows are some more advanced options if you’d like to explore VirtualBox further.