Brightness screen

Hi new to this forum.
Have just got a pi top. Think it’s the older version with touchpad to right of keyboard.
The sad cad that came didn’t work. Just sat on rainbow screen. So I downloaded image.
Runs ok but not possible to change brightness with buttons or on slider in settings… any ideas

@Late_voyager which OS image did you download?

It’s surprising that the buttons don’t work, they are connected directly to the hardware so the brightness should change regardless of which OS is running