\documentclass{beamer}

\begin{document}
  
\begin{frame}[fragile]{Opciones de {\tt\bf templates}}

  \begin{exampleblock}{Símbolos de navegaci\'on}
    \scriptsize
    \begin{semiverbatim}
  \\setbeamertemplate\{navigation symbols\}[default]
  \\setbeamertemplate\{navigation symbols\}[vertical]
  \\setbeamertemplate\{navigation symbols\}[only frame symbol]
  \\setbeamertemplate\{navigation symbols\}\{\} \end{semiverbatim}
  \end{exampleblock}
  
  \begin{exampleblock}{Bloques}
    \scriptsize
    \begin{semiverbatim}
  \\setbeamertemplate\{blocks\}[rounded]
  \\setbeamertemplate\{blocks\}[default]
  \\setbeamertemplate\{blocks\}[rounded][shadow=true] \end{semiverbatim}
  \end{exampleblock}
  
  \begin{exampleblock}{Listas}
    \scriptsize
    \begin{itemize}
      \item \begin{semiverbatim}\\setbeamertemplate\{items\}[circle]\end{semiverbatim}
      \item \begin{semiverbatim}\\setbeamertemplate\{items\}[ball]\end{semiverbatim}
      \item \begin{semiverbatim}\\setbeamertemplate\{items\}[square]\end{semiverbatim}
    \end{itemize}
  \end{exampleblock}
  
  El comando \emph{\tt setbeamertemplate} se pone en el pre\'ambulo o dentro del documento (pero fuera de los frames).
  
\end{frame}

\end{document}
