Beamer presentation: Problem with captions

Question

I am making a presentation and I have two issues there: 1) I need to use the package subcaption to make subfigures, while simultaneously I want to use the command from this site \setbeamertemplate{caption}{\raggedright\insertcaption\par} to get rid of "Figure:" before the figure caption. However, when I use the package subcaption, the latter command stops working and I can still see "Figure:" before the caption - see the first image.

Do you know how to make "Figure:" dissapear and still use subcaption package?

2) Why is the distance between caption and the figure so long in the image below? (last few lines of the code) The code for this figure is the same as the code for the first figure, so I don't understand why there are such differences in the distance of caption from the figure.

The code is:

\PassOptionsToPackage{table}{xcolor}
\documentclass[xcolor=svgnames]{beamer}

%\PassOptionsToPackage{svgnames}{xcolor}
%\documentclass[xcolor=table]{beamer}
%
% Choose how your presentation looks.
%
% For more themes, color themes and font themes, see:
% http://deic.uab.es/~iblanes/beamer_gallery/index_by_theme.html
%
\mode<presentation>
{
  \usetheme{Warsaw}      % or try Darmstadt, Madrid, Warsaw, ...
  \usecolortheme{default} % or try albatross, beaver, crane, ...
  \usefonttheme{default}  % or try serif, structurebold, ...
  \setbeamertemplate{navigation symbols}{}
%  \setbeamertemplate{caption}[numbered]
%\setbeamercolor{section in head/foot}{bg=NavyBlue}
}

\usepackage[english]{babel}
\usepackage[utf8x]{inputenc}
\usepackage{graphicx}
\usepackage{hyperref}
\usepackage{amsmath}
\usepackage{xcolor}
\usepackage{tabu}
\usepackage{booktabs}% for better rules in the table
\usepackage{ragged2e}
\usepackage{rotating}
\usepackage{threeparttable}
\usepackage{subcaption}


\title[Thesis Defense]{Name of thesis}
\subtitle{Thesis Defense}
\author{name}
 \institute{University}
\date{January 31, 2018}

\begin{document}
\setbeamertemplate{caption}{\raggedright\insertcaption\par}
\setbeamerfont{caption}{size=\tiny}
\setlength{\abovecaptionskip}{-2pt}
\setlength{\belowcaptionskip}{6pt}



\begin{frame}[plain]
  \titlepage
\end{frame}

\begin{frame}{Motivation}
\begin{figure}[!t]
\centering

\begin{measuredfigure}
\includegraphics[width=\linewidth,height=0.5\textheight,keepaspectratio]{WuXia_rate_Real_HPI}
\caption{\textit{Shaded area marks the pre-crisis period in which effective federal funds rate was below the Taylor rule rate.}}
\end{measuredfigure}

\end{figure}

\begin{itemize}
\item 
\item 
\end{itemize}

\end{frame}


\begin{frame}{Results - Impulse responses, baseline model}

\begin{figure}[!htb]
\begin{footnotesize}
\centering
\begin{subfigure}{.5\textwidth}
  \centering
  \includegraphics[height=0.3\textheight,width=\linewidth,keepaspectratio]{IRF_baseline_big_November2006}
%  \vspace{-3mm}
%
%  \hspace{5mm} \small{November 2006}
  %\caption{November 2006}
  %\label{fig:}
\end{subfigure}%
\begin{subfigure}{.5\textwidth}
  \centering
  \includegraphics[height=0.3\textheight,width=\linewidth,keepaspectratio]{IRF_baseline_big_July2007}
%  \vspace{-3mm}
%
%  %\caption{}
%  \hspace{5mm} \small{July 2007}
  %\label{fig:}
\end{subfigure}
\begin{subfigure}{.5\textwidth}
  \centering
  \includegraphics[height=0.3\textheight,width=\linewidth,keepaspectratio]{IRF_baseline_small_October2008}
%  \vspace{-6mm}
%
%  %\caption{}
%  \hspace{5mm} \small{October 2008}
  %\label{fig:}
\end{subfigure}%
\begin{subfigure}{.5\textwidth}
  \centering
  \includegraphics[height=0.3\textheight,width=\linewidth,keepaspectratio]{IRF_baseline_big_August2011}
%  \vspace{-6mm}
%
% % \caption{}
% \hspace{5mm} \small{August 2011}
  %\label{fig:}
\end{subfigure}
\begin{subfigure}{.5\textwidth}
  \centering
  \includegraphics[height=0.3\textheight,width=\linewidth,keepaspectratio]{IRF_baseline_small_December2013}
%  \vspace{-6mm}
%
%  %\caption{}
%  \hspace{5mm} \small{December 2013}
  %\label{fig:}
\end{subfigure}%
\begin{subfigure}{.5\textwidth}
  \centering
  \includegraphics[height=0.3\textheight,width=\linewidth,keepaspectratio]{IRF_baseline_small_April2017}
%  \vspace{-6mm}
%
%  %\caption{}
%  \hspace{5mm} \small{April 2017}
  %\label{fig:}
\end{subfigure}
%\label{fig:IRF_baseline}
\end{footnotesize}
\end{figure}

\end{frame}


\begin{frame}{Results - FEVD}

\begin{figure}[!t]
\centering

\begin{measuredfigure}
  \includegraphics[width=\linewidth]{FEVD_baseline_small_April2017}
\caption{Some caption...}
\end{measuredfigure}

\end{figure}


\end{frame}



\end{document}

Answer 1

Instead of the subcaption package you could simply use beamers column mechanism in order to place your images.

Please note that you don't need \usepackage{graphicx}, \usepackage{hyperref} or \usepackage{xcolor} with beamer. \usecolortheme{default} and \usefonttheme{default} are called default, because they are loaded per default, so no need to load them a second time. And giving floating specifier (such as [!htb]) does not make sense in a class that does not have floating objects.

\PassOptionsToPackage{table}{xcolor}
\documentclass[xcolor=svgnames]{beamer}

\mode<presentation>
{
  \usetheme{Warsaw}  
  \setbeamertemplate{navigation symbols}{}
}

\usepackage[english]{babel}
\usepackage[utf8x]{inputenc}
%\usepackage{graphicx}
%\usepackage{hyperref}
\usepackage{amsmath}
%\usepackage{xcolor}
\usepackage{tabu}
\usepackage{booktabs}% for better rules in the table
\usepackage{ragged2e}
\usepackage{rotating}
\usepackage{threeparttable}
%\usepackage{subcaption}

\setbeamertemplate{caption}{\raggedright\insertcaption\par}
\setbeamerfont{caption}{size=\tiny}
%\setlength{\abovecaptionskip}{-2pt}
%\setlength{\belowcaptionskip}{6pt}

\title[Thesis Defense]{Name of thesis}
\subtitle{Thesis Defense}
\author{name}
\institute{University}
\date{January 31, 2018}

\begin{document}

\begin{frame}{Results - Impulse responses, baseline model}

\begin{figure}
\setbeamerfont{caption}{size=\footnotesize}
\begin{columns}[onlytextwidth]
    \begin{column}{.45\textwidth}
        \centering
        \includegraphics[height=0.2\textheight,width=\linewidth,keepaspectratio]{example-image}
        \includegraphics[height=0.2\textheight,width=\linewidth,keepaspectratio]{example-image}
        \includegraphics[height=0.2\textheight,width=\linewidth,keepaspectratio]{example-image}
    \end{column}
    \begin{column}{.45\textwidth}
        \centering
        \includegraphics[height=0.2\textheight,width=\linewidth,keepaspectratio]{example-image}
        \includegraphics[height=0.2\textheight,width=\linewidth,keepaspectratio]{example-image}
        \includegraphics[height=0.2\textheight,width=\linewidth,keepaspectratio]{example-image}
    \end{column}    
\end{columns}   
\caption{whatever caption you want}
\end{figure}

\end{frame}

\end{document}