Since I updated my PhpStorm, whenever I type a method, it mentions me the parameter hint.
Like so:
I wanted to know if there's a way to change its style.
The reason why I couldn't find an option to change the style of the parameter hint, was because I was looking on a PHP code style instead of a general font style.
Going to Settings > Editor > Colors & Fonts > General
and then choosing the "Parameter Hint" and that's it.