If you want to use any keyboard shortcuts in VirtualBox, you must use the Host key in combination with another key. By default, the Host key is the right Ctrl key on your keyboard.
There may be some keyboards, such as laptop keyboards, that do not have the right Ctrl key. If you are in such a situation, or prefer to use another key as the host key, this post describes how to change the key on your keyboard that is used as the host key.
Change the host key in VirtualBox
To change the host key, open VirtualBox. Select “Preferences” from the “File” menu.
The Options dialog box opens. Click an input option in the left pane. On the entry screen, click the box next to Host Key. Enter the new desired key.
NOTE. Alphanumeric keys, arrow keys, and edit keys cannot be used as host keys.
The new key is displayed in the box next to the Host Key. Click OK.
The host key is displayed in the lower right corner of the VirtualBox status bar in case you forget which key you selected as the host key.
On the input screen, you can also choose to automatically capture the keyboard when you open the virtual machine. To do this, select the “Auto-capture keyboard” checkbox. This means that all keystrokes are directed to the virtual machine until you press a host key to return mouse and keyboard control to the host machine.
Also, be sure to check out my other posts on VirtualBox, such as how to install Ubuntu in VirtualBox, how to share folders between guest and host, and how to hide the menu and status toolbars in VirtualBox Enjoy!