SE2419H, no audio?

I have a new Dell monitor, attached to an older Dell laptop (Windows 10) with a new HDMI cable.  I downloaded the driver and manual from Dell, and I've gone through it. I have looked at device settings and various Windows settings, and gone through the troubleshooters, but the only useful information I found was on one screen it said there are no audio devices installed. Sound works fine when I choose the laptop's integrated audio, but there is nothing through the monitor. The option for this monitor as an audio device is shown on the Windows start menu bar on the right, but tests result in no sound. At first I thought the monitor did not have sound itself, there are no input points for headphones or speakers I can find (or shown in the manual). But other internet sources say this monitor does have sound/speakers. On the monitor's setup menu (bottom right), there is no item for Audio between Display and Menu. On the audio driver when I selected the monitor as a device, it looks like it is using a Microsoft driver. I installed the Dell monitor driver a few times, but it still doesn't show Dell as the device. On Windows 7 I know how to disable drivers etc., but not on Windows 10. I don't have a VGA cable (or an alternative HDMI cable) to test but if this is the only way to get audio to work, I'll buy one. I tried to contact support with the service tag but it says there is no such tag. Does Dell not support even brand new products?