Sound settings beyond 100 percent not kept after reboot

[Ewgenijkkg]

Hello, guys. I installed Linux Mint on the laptop of my mother. She likes watching different online films, however the sound is too low. Thus, I increased its level in the sound menue beyond 100 percent. It worked fine. But after reboot the setting is not kept. I got to set it over and over again. Is it a bug or a feature? What is the reason for such an automatic reset?

BR
Ewgenij