How to change the color of a block within a custom Beamer .sty theme file?

Question

I'm in the process of creating a custom Beamer theme. I know how to change the color of fonts for certain elements within an itemize or enumerate block, but I can't seem to figure out how to specific the color in a block as depicted below. For example:

\begin{block}{Change the font color here}
    some text
    some more text
\end{block}

I would like to alter the color of the {Change the font color here} area for my theme. I am trying to use this code in my .sty file to change the color to black:

\setbeamercolor{block}{fg=black}

What am I doing wrong?

Answer 1

I think I totally misunderstood this question, but for what it's worth, here's my answer to (what I thought was) the question.

You could define another environment like so:

\newenvironment{variableblock}[3]{%
  \setbeamercolor{block body}{#2}
  \setbeamercolor{block title}{#3}
  \begin{block}{#1}}{\end{block}}

Then you can set the colours of the blocks as optional arguments:

\begin{variableblock}{Title}{bg=blue,fg=white}{bg=green,fg=red}
  Stuff
\end{variableblock}

This makes the background of the body blue and the background of the title block green. It also makes the body text white and the block title text red.

Answer 2

You can modify the color using the block title template:

\documentclass{beamer}

\setbeamercolor{block title}{bg=red!30,fg=black}

\begin{document}

\begin{frame}
\begin{block}{Change the font color here}
    some text
    some more text
\end{block}
\end{frame}

\end{document}

Answer 3

You can also wrap the \setbeamercolor statement within a {} group. The change is only local

{
\setbeamercolor{block}{bg=red, fg=white}
\begin{block}{}
...
\end{block}
}

For temporary use, say highlighting something, you can also use

\only<1,3,7>{
\setbeamercolor{block}{bg=red, fg=white}
    }