I want to change my list enumerator style from 1, 2, 3 to be like (1), (2), (3) … in LyX. Here how I change it in Lyx:

In preamble Latex, add this line:

\usepackage{enumerate}
\renewcommand{\labelenumi}{(\arabic{enumi})}


if you want to get (a), (b), (c)… , then you can change the \arabic with \alph or change others thing you want.

I found a blog with more examples here. You can take a look there if my code didn’t solve your problem, because I’m a new beginner with LaTeX stuff.