Dell All-In-One display control - Inspiron 27-7700

[Steerpike]

Perhaps a long-shot for a notebook forum, but my g/f just bought the Dell All-In-One Inspiron 27-7700 so she could have a really neat, 'no wires' look for her work area while still having a large display.  It's working fine, and it does look remarkably neat I have to say. It has a 'touch screen'. 

 

Today we went to plug in her Nintendo game device into the "HDMI In" port on the back. This AIO computer has precisely TWO buttons on it - 1 for power, 1 for display.  A short-press on the display button toggles the screen between external input and internal input. A 'long press' of the same button turns off the display.  But I cannot figure a way to get brightness control or volume control for the display/speakers when it is switched to the external source!  Dell support provide an 'on screen display driver' for this machine, which I have applied but there's no change. And they don't tell you 'how' this driver is supposed to work - does it present an on-screen-menu for touch-control of the brightness? Magically make use of the two buttons on the machine ...? 

[Aaron44126]

BIOS setup display/video section might have an option to set the “default” brightness of the built-in display …?

 

(Never seen one of these.  My best guess.)