im trying to change the fonts of the game, and i follow the instructions of changing and renaming 4 files (ttp). whenever i open the game, a slug file always appears in my folder, and the fonts stay the same all the time.
Changing fonts does not require you to alter any game files.
The .slug files in the Fonts folder should not be an issue. The Fonts you add should over rule them. Check you have named your custom font files correctly (case matters) and the files are .ttf (True Type Fonts).
WoWheads guide:
Note that addons can change your fonts too and can over rule the custom fonts you add in the fonts folder. So if you think everything should be working then disable your addons, logout, delete the .slug files and login again to see if that works. (Addons could be the ones creating the .slug files).