Why can't I change the game's priority in the task manager?

[S.T.A.R.S]

I like to play the game while a youtube video is playing on the other monitor, but that causes the game to lag and causes skill checks button press delay, I could easily increase the fps while watching the video by changing the game's task priority to high, however, the game doesn't allow me to do so, I get an error, and I am sure that it is programmed that way for some reason...

Let me change the game's priority in the task manager like I am supposed to, it is my computer and I have all the right to set what the applications priorities are, remove this restriction.

[A Generic Name]

I believe that has something to do with EAC rather than DBD itself. Try changing the priority for Steam before launching the game, DBD should then inherit the priority properties of Steam.