The default screen resolution running Ubuntu on Virtualbox is a 4:3 ratio. So how do you change this? The solutions found on the web are slightly cryptic and the entire fix is not available in one place. So here it is short and sweet:
- Run you Ubuntu Virtualbox
- If the Virtualbox top-bar menu is not visible after launching, you are likely in scale mode and need to close that using Host+C keyboard shortcut (ie Right-Control + C)
- Select Devices > Insert Guest Additions CD Image – Guest additions came packaged with your Ubuntu download. It can take a couple of minutes for this to run.
- Restart Ubuntu
The resolution should scale accordingly now.
This solution worked with Virtualbox 4.3.20 and Ubuntu 14.04.