Well, my problem is that I press the volume control on the keyboard, I see the bar in the screen going down, but it doesn't do anything until it's at 0. So the volume is on 0 or 100%.
I have done many things trying to fix it. Finally, I did something that I read here How do I change the way Ubuntu adjusts my volume mixer levels? , and it works, but not forever. For example, the solution just remains one song in YouTube. After that, again, very loud sound or silence. I go by the terminal to check /etc/pulse/default.pa and everything is ok, like I left it before.
I don't know what to do. I'm getting crazy.
Thank you so much for your time!
EDIT: I had Windows 10 before in this PC, but I reformatted to Ubuntu 18.04.3 LTS. The model is an ASUS ZENBOOK UX490U. And finally, typing lspci -v | grep -i vga in the terminal, I get this:
00:02.0 VGA compatible controller: Intel Corporation HD Graphics 620 (rev 02) (prog-if 00 [VGA controller])
