With `\setbeamercolor{normal text}{fg=white,bg=black}`:
\documentclass[usenames,dvipsnames]{beamer}
\usepackage[absolute,verbose,overlay]{textpos}
\usepackage[utf8x]{inputenc}
\usepackage{pgfpages}
\usepackage{beamerthemeWarsaw}
\usepackage{colortbl}
\usepackage{graphicx}
\usepackage{fancyvrb}
\useoutertheme[subsection=false]{smoothbars}
\setbeamertemplate{navigation symbols}{}
\setbeamercolor{background canvas}{bg=black}
\setbeamercolor{background}{bg=black}
\setbeamercolor{title}{parent=structure,fg=white,bg=yellow}
\setbeamercolor{titlelike}{parent=structure,fg=white,bg=yellow}
\setbeamercolor{structure}{fg=white,bg=black}
\setbeamercolor{frametitle}{fg=white,bg=black}
\setbeamercolor{headline}{fg=yellow,bg=yellow}
\setbeamercolor{upper separation line head}{fg=yellow}
\setbeamercolor{separation line}{fg=yellow}
\setbeamercolor{fine separation line}{fg=yellow}
\setbeamercolor{normal text}{fg=white,bg=black}
\setbeamercolor{block title}{use=structure,fg=white,bg=black}
\setbeamercolor{block body}{use=structure,fg=white,bg=yellow}
\setbeamercolor{title in head/foot}{fg=white}
\begin{document}
\author{Sivaram,\\ \color{RoyalBlue}{***@null.com}}%
\date{\today }%
\title[MWE\hspace{10em} \insertframenumber\ of
\inserttotalframenumber]{MWE}
\institute{MWE}
\begin{frame}
\titlepage
\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{frame}
\frametitle{Sample header}
The line above should be yellow
\end{frame}
\end{document}
Post by Sivaram Neelakantan\documentclass[usenames,dvipsnames]{beamer}
\usepackage[absolute,verbose,overlay]{textpos}
\usepackage[utf8x]{inputenc}
\usepackage{pgfpages}
\usepackage{beamerthemeWarsaw}
\usepackage{colortbl}
\usepackage{graphicx}
\usepackage{fancyvrb}
\useoutertheme[subsection=false]{smoothbars}
\setbeamertemplate{navigation symbols}{}
\setbeamercolor{background canvas}{bg=black}
\setbeamercolor{background}{bg=black}
\setbeamercolor{title}{parent=structure,fg=white,bg=yellow}
\setbeamercolor{titlelike}{parent=structure,fg=white,bg=yellow}
\setbeamercolor{structure}{fg=white,bg=black}
\setbeamercolor{frametitle}{fg=white,bg=black}
\setbeamercolor{headline}{fg=yellow,bg=yellow}
\setbeamercolor{upper separation line head}{fg=yellow}
\setbeamercolor{separation line}{fg=yellow}
\setbeamercolor{fine separation line}{fg=yellow}
\setbeamercolor{normal text}{fg=white}
\setbeamercolor{block title}{use=structure,fg=white,bg=black}
\setbeamercolor{block body}{use=structure,fg=white,bg=yellow}
\setbeamercolor{title in head/foot}{fg=white}
\begin{document}
\date{\today }%
\title[MWE\hspace{10em} \insertframenumber\ of
\inserttotalframenumber]{MWE}
\institute{MWE}
\begin{frame}
\titlepage
\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{frame}
\frametitle{Sample header}
The line above should be yellow
\end{frame}
\end{document}