change figure caption size doesn't work

I am using this code (metropolis) .

Whatever I used in order to change the figure caption size, doesn’t work.

documentclass[10pt] {beamer}  
usepackage[utf8]{inputenc}
usepackage {graphicx, beamerthemesplit}

newcommand{textgreek}[1]
    {bgroupgreekfont{#1}egroup} % Greek text

newenvironment{greekpar}           % Greek paragraph
    {greekfont}{}


setbeamerfont{caption}{size=Tiny}
%usepackage[textfont={small}]{caption}
%usepackage{caption}
%captionsetup[figure]{font=small}

%DeclareCaptionFont{8pt}{fontsize{8pt}{8pt}selectfont}
%captionsetup{font=8pt}

usetheme[progressbar=frametitle]{metropolis}
definecolor{mpigreen}{HTML}{007977}

setbeamercolor{frametitle}{bg=mpigreen}
setbeamertemplate{blocks}[rounded][shadow]

setbeamercolor{block body alerted}{bg=alerted text.fg!10}
setbeamercolor{block title alerted}{bg=alerted text.fg!20}
setbeamercolor{block body}{bg=structure!10}
setbeamercolor{block title}{bg=structure!20}
setbeamercolor{block body example}{bg=green!8}
setbeamercolor{block title example}{bg=mpigreen, fg=white}

newenvironment<>{question}[1]{%
  begin{actionenv}#2%
      definsertblocktitle{#1}%
      par%
      mode<presentation>{%
        setbeamercolor{block title}{bg=mpigreen, fg=white}
       setbeamercolor{block body}{bg=blue!8}
       setbeamercolor{itemize item}{fg=green!20!black}
       setbeamertemplate{itemize item}[circle]
     }%
      usebeamertemplate{block begin}}
    {parusebeamertemplate{block end}end{actionenv}}
    
title [Data]{Data}
author {George}
date {19/04/2021}

begin{document}  

    begin{frame}
    titlepage 
    end{frame}

    begin{frame}{Data}
        begin{columns}
            begin{column}{0.4textwidth}
                
            begin{question}{Ερώτηση}
                begin{itemize} 
                item Ποιος ειναι ...
                                
                item μπλα μπλα
                
                end{itemize}
            end{question}

        
            end{column}
            
            begin{column}{0.7textwidth}
            begin{figure}
                includegraphics[width=0.7textwidth, height=0.5textwidth]{./11.jpeg}
                caption{ΜΟ εδώ πολύ μεγάλο}
                label{fig:mean_spray}
            
                
            
                includegraphics[width=0.7textwidth, height=0.3textwidth]{./22.jpeg}
                caption{Και εδώ τα ίδια}
                label{fig:nb_diseases}
            end{figure}
            
            end{column}
            end{columns}
    end{frame}
end{document}

documentclass{beamer}  

usetheme[progressbar=frametitle]{metropolis}
setbeamerfont{caption}{size=Tiny}

begin{document}  

begin{frame}
Normal text.
    begin{figure}
    includegraphics[width=0.5textwidth]{example-image}
    caption{Foo bar baz.}
    end{figure}
end{frame}

end{document}