Without you realize, when you create a new VM in VirtualBox, you will use the minimum resolution, how to increase virtual machine resolution on VirtualBox for optimal graphics and especially for run it in full screen?
No problem VirtualBox allows you to change the settings to increase dedicated video memory to your virtual machine.
How to increase virtual machine resolution on VirtualBox in 2 steps
Before you start make sure the virtual machine you’re trying to edit is shut down (does not stop at the last saved point), otherwise the settings will not be editable
Step 1. Open your Virtual machine settings
From the VirtualBox main menu, select the virtual machine you want to edit, press the right mouse button and select Settings… (using keyboard shortcuts Ctrl + S)
Step 2. Change the Display settings
From the left menu select the Display tab, now increases the cursor of the video memory to a maximum of 128MB and click OK to save changes.
From now on the virtual machine that you edited will use 128MB of VRAM
How to increase virtual machine resolution on VirtualBox beyond the limit of 128MB?
Even increasing the memory, VirtualBox allows a maximum use of VRAM in virtual environments limited to 128MB. This obstacle, however, may be overridden with additional commands.
Step 1. Open windows console
Open Windows command prompt and placed in directory where you installed VirtualBox, usually “C:\Program Files\Oracle\VirtualBox”, so in this case type
cd "C:\Program Files\Oracle\VirtualBox"
Step 2. Increase video memory to 256MB
To increase video memory uses vboxmanage command in the following format
vboxmanage modifyvm "virtual-machine-name" --vram new-value-in-MB
Replace “virtual machine name” with the name of the VM you want to edit and “new value in MB” to 256
vboxmanage modifyvm Kali --vram 256
At this point the virtual machine called Kali has been set to use 256MB of video memory.
Do not exceed in any case the 256MB, otherwise VirtualBox will return an error.