The photo below describes my question. I checked but could not find a duplicate question
\documentclass[12pt, xcolor=dvipsnames]{beamer}
\beamertemplatenavigationsymbolsempty %no navigation pane
\usetheme{CambridgeUS}
\usecolortheme{seahorse}
\title[A Smaller Title]{Title for the Presentation}
\author[John Doe]{John Doe}
\institute[]{\includegraphics[height=1.5cm]{image-placeholder.jpg}}
\date[{\includegraphics[height=2mm]{image-placeholder.jpg}}]{Some Day in 2021}
\begin{document}
\begin{frame}[noframenumbering, plain]
\titlepage
\end{frame}
\section{some section}
\subsection{some subsection}
\begin{frame}{\centerline{A Long Title Here But Does Not Look Centered}}
I was wondering why the long title does not look centered, and what can I do to make it centered.
\end{frame}
\end{document}

\setbeamertemplate{frametitle}[default][center]as for example described here: How do I horizontally center the title in a slide, here: Beamer query, center justify \frametitle or here: Centered frame title in beamer – leandriis Feb 26 '21 at 21:38\setbeamertemplate{frametitle}[default][center]to the preamble of your document, also remove the\centerlinecommand from the frametitle. Using\begin{frame}{A Long Title Here But Does Not Look Centered}should result in a horizontally centered frame title. – leandriis Feb 27 '21 at 09:26\centerlineseems to be the real culprit. Thanks, it works perfectly fine right now. – Semzem Mar 02 '21 at 20:36