Where do I put the r.Mac.OpenGLDisabled=0 code?

I looked at another forum and it told me to put “r.Mac.OpenGLDisabled=0” inside the DefaultGame.ini file. I then changed it to a .docx file. But, I don’t know where to put the “r.Mac.OpenGLDisabled=0” code. If anybody knows, please answer me ASAP.

(Im trying to play Fortnite)