У вашего броузера проблема в совместимости с HTML5
When you can't change a parameter in Pro Tools, it is likely due to the fact that you have automation written on that parameter somewhere on your track. This video covers how to clear automation in your project.
Change the view of the tracks you want to delete automation for to an automation layer such as Volume, select the section you want to clear automation for and press CTRL + delete (backspace) for Mac, Start+delete (backspace) for Windows.