The brightness of the VBOX Touch screen can be adjusted by pressing the Settings Button on the bottom left of the screen, and then using the Forward arrow or swiping the screen to the left to navigate to the General Settings menu.
You can manually adjust the screen brightness between 5 levels, with 1 being the dimmest and 5 being the brightest setting. An 'Auto' setting is also available which uses the internal ambient light sensor to automatically adjust the screen brightness. In dark conditions, the screen brightness will dim, and in light conditions the screen will brighten. Tap the button to cycle through the available options.