LaTeX: Change subsection numbering

If you want to change the subsection numbering, you have to renew the command first as follows:

\renewcommand\thesection{\roman{section}}
\renewcommand\thesubsection{\thesection.\roman{subsection}}

with similar commands like \thesubsubsection and so on 

of course, there's also \thechapter (in the book and report class) and \thepart.

Commands to typeset numbers include:

• \arabic (1, 2, 3, ...)
• \alph (a, b, c, ...)
• \Alph (A, B, C, ...)
• \roman (i, ii, iii, ...)
• \Roman (I, II, III, ...)
• \fnsymbol (∗, †, ‡, §, ¶, ...)
•  

If you want to change numbering in \enumerate, use this:

\usepackage{enumerate}
.
.
.
\begin{enumerate}[(a)] % (a), (b), (c), ...
\item
\end{enumerate}
.
.
.
\begin{enumerate}[a)] % a), b), c), ...
\item
\end{enumerate}