- Download the latest version of VirtualBox at: https://www.virtualbox.org/wiki/Downloads.
- Right Click on the Downloaded Package and Select 'Open With > Ubuntu Software Center.'
- Now VirtualBox should be Updated.
Once you Update VirtualBox and Open it you will get a prompt to Update your Guest Additions as well. Simply follow the instructions in the simultaneous dialog box that prompts in your screen and Update the Guest Additions as well.