Final answer:
To increase storage in VirtualBox Ubuntu, you need to shut down the VM, modify the disk size through VirtualBox Manager, and then resize the Ubuntu partition using a tool like GParted.
Step-by-step explanation:
To increase storage in VirtualBox Ubuntu, you need to first power off the virtual machine. Then, in the VirtualBox Manager, select the virtual machine and click on 'Settings'. Under 'Storage', select the virtual disk you want to resize and click on the 'Properties' icon. You'll see a slider or a field where you can specify the new size of the virtual disk. Keep in mind that this process will increase the maximum capacity of the disk, but you will also need to resize the partition within Ubuntu for the operating system to recognize the additional space.
To resize the partition within Ubuntu, you can use tools like 'GParted', which is a graphical partition editor. Boot the virtual machine with a GParted live CD or ISO and resize the main partition to fill up the newly created space. Once completed, shut down the live session and restart your Ubuntu virtual machine. Ubuntu should then be able to use the new disk space.