In Windows 10, the volume is always automatically louder and quieter?

Today I have a problem with my win 10 notebook, where there are always some problems with the sound on certain pages (like Youtube).

The sound is always automatically lower and then louder…

Please help me.

Thanks in advance.

Edit: It has now become clear that I have loose contact with my headphones.

Will only the sound be louder and softer, or will the volume setting change automatically?

So it is "automatically" quieter and then put back to the normal volume, without this you see the speaker icon

See if your affected sound device has a driver setting for "Smart Volume" or similar.

I think, I have to buy new headphones, because the sound is only quieter and then louder… (My headphones have loose contact, which I have just found out now)

I'm sorry about the circumstances…