Laptop and TV connected to HDMI: Why do I have a picture but no sound?

When I connect my Lenovo laptop to the television via HDMI, I see a picture but have no sound on the television. I've googled for hours but no solution worked.

When I open the playback devices via the sound menu, no HDMI output is displayed, only "Speakers - Realtek High Definition Audio". I have already activated "Show deactivated and separated devices" by right-clicking, but it only shows me the standard speaker. I have already checked the graphics card and sound for current drivers in the device manager - everything is up to date. It is also not due to the cable or television, as the sound works with another laptop.

I'm slowly desperate. Does anyone know what else I can do to get the sound through to the TV too?

I have the Windows 10 operating system and the Lenovo V340-17IWL laptop. The drivers for my laptop are listed on the Lenovo site, but I also don't know which one to install:
https://pcsupport.lenovo.com/...iver-list/

I would suspect the correct driver is not installed.
If it is an integrated GPU you will need the chipset driver. If it's Nvidia the graphics driver.
Realtek Audio is definitely wrong.

Thanks for the answer. I don't have Nvidia, but Intel UHD graphics. Do you know which driver I would have to install from the homepage?

The chipset driver

That probably won't help you now, but I also have a notebook with Intel and Nvidia graphics, only the Realtek sound is listed there. But I don't know why. On my PC, an audio output appears for each graphics connection.

It's the same with my other laptop with Nvidia and Intel. Nevertheless, the HDMI cable works there. Strange! Thanks for your help! I'll try that with the driver.