Question for MAC OS users

Hello everyone. So, after a very long break I wanted to play some Wow. Atm I own a macbook pro late 2015 13" and as you know it isnt suitable for gameing. However, I played few days on retail where I can set FPS cap ingame, I found this prevent this from overheating. I wanna play some WOTLK, and this expension doesn't have the ingame option to set a fps cap. So, Ive tried in WTF file, where I put those 2 setting, I saved, then entered the game to find that the fps was still 60. So I got back in WTF, and those 2 setting I wrote dissapeared. Is there anyone facing the same problem/ know how to fix this?
Thanks guys.