How to change the color of the text in a theorem in beamer?

Question

Hello I'm writing a beamer presentation and I would like to change the colour of the text in the theorem block from one place and it will affect my whole presentation.

Is this possible?

My example:

\documentclass{beamer}

 \usetheme{Madrid}

 \usecolortheme[RGB={201,20,35}]{structure} 
 \setbeamercolor{background canvas}{bg=black}
 \setbeamercolor{normal text}{fg=white} 
 \setbeamercolor{theorem text}{fg=black} 

 %\useoutertheme{shadow}
 \useinnertheme{rounded}

 \usepackage[utf8]{inputenc}
 \usepackage{default}

 \begin{document}

 \begin{frame}{Primul Slide}

 Bla bla bla 

 Bla bla bla 
 \begin{theorem}
 This is a theorem it is very important!!
 \end{theorem}

 \end{frame}

 \end{document}

Answer 1

One possibility would be to set the block body and/or block title colors to produce the desired result; since the modification must affect only theorems, the etoolbox package can be used to patch the required environments; a little example using the settings provided in the question:

\documentclass{beamer}
\usepackage{etoolbox}

 \usetheme{Madrid}

\usecolortheme[RGB={201,20,35}]{structure} 
\setbeamercolor{background canvas}{bg=black}
\setbeamercolor{normal text}{fg=white} 

\AtBeginEnvironment{theorem}{%
  \setbeamercolor{block body}{fg=black,bg=blue!40}
}

\begin{document}

\begin{frame}{Primul Slide}
test text
\begin{theorem}
This is a theorem it is very important!!
\end{theorem}
\end{frame}

\end{document}

Notice that I suppressed

\setbeamercolor{theorem text}{fg=black} 

from the original code and changed the font color using

\setbeamercolor{block body}{fg=black,bg=blue!40}