virtual box screen size code example

Example 1: virtualbox screen size too small

follow the steps:
It is recommended that you set 128 MB of video memory, as when a video mode with higher resolution is used, more video memory is needed. You can also enable 2D and 3D acceleration.

open cmd:
cd "c:\Program Files\oracle\virtualbox"
VBoxManage setextradata "NAMEOFVM" VBoxInternal2/EfiGraphicsResolution 1920x1080

Example 2: how to increase the screen size in virtualbox

sudo apt-get install virtualbox-ose-guest-utils virtualbox-ose-guest-x11 virtualbox-ose-guest-dkms