The following minimal working example shows how one can change bullet style of different itemize levels using \setbeamertemplate
command:
% Bullet style in Beamer \documentclass{beamer} % Theme choice \usetheme{CambridgeUS} % set the itemize item symbol as a diamond \setbeamertemplate{itemizeitem}{\scriptsize$\diamond$} % set the itemize subitem symbol as a triangle \setbeamertemplate{itemize subitem}{\scriptsize$\blacktriangleright$} % set the itemize subsubitem symbol as a circle with a dot \setbeamertemplate{itemize subsubitem}{\scriptsize$\odot$} \begin{document} \begin{frame} \frametitle{Bullet style in Beamer} \begin{itemize} \item Level 1 \begin{itemize} \item Level 2 \begin{itemize} \item Level 3 \end{itemize} \end{itemize} \end{itemize} \end{frame} \end{document}
Compiling this code yields:

We used diamond shape for main items, right triangle for subitems and a circle with a dot for subsubitems.
For more details, I invite you to check Lists in Beamer – Complete Guide.