I am using Virtual Box 5.0.0(Windows Vista) to run Ubuntu 14.04. The screen is too small (640x480) but the screen can up to 1280x768. How can I resizing it?
I encountered the same problem on my PC recently. This is my solution;
Go to the Ubuntu machine:
Settings ⇒ Display ⇒ Graphics controller ⇒ Choose (VBoxSVGA or VBoxSVGA)
My original settings which caused the problem was
This solution worked on my PC. I cannot guarantee that it will work on yours.