Superman (imported from SE)
I am using the hyperref package, and here is my code:


\documentclass[12pt]{beamer}
\usepackage{float}
\usepackage{amsmath}
\usepackage{pgfpages}
\pgfpagesuselayout{resize to}[a4paper,landscape]
\usefonttheme{professionalfonts} %To get the accents aligned correctly, albeit in Computer Modern Roman
\usepackage{hyperref}
\hypersetup{
%filecolor=magenta,
%urlcolor=cyan,
urlcolor=blue,
}

\setbeamertemplate{footline}
{
\leavevmode%
\hbox{%
\end{beamercolorbox}%
\end{beamercolorbox}%
\end{beamercolorbox}}%
\vskip0pt%
}

\title{Test}				% used by \maketitle
\author{John Doe }
\date{Spring 2020}					% used by \maketitle
\institute{John Doe University}
\begin{document}
\setcounter{section}{5}
\maketitle					% automatic title!
\begin{frame}
Click on this link: \href{https://ocw.mit.edu/courses/aeronautics-and-astronautics/16-323-principles-of-optimal-control-spring-2008/lecture-notes/lec5.pdf}{MIT OpenCourseWare, Page 5-18}
\end{frame}
\end{document}



Output:

[![enter image description here][1]][1]

As one can see, the title in the footer gets highlighted red due the the hypersetup command, and the URL description gets highlighted as expected, but clicking on the description doesn't do anything. I have two questions:

1. How to enable only the URL description to be colored and disable the title coloring in the footer?
2. How to enable the URL description so that when clicked on, the person gets directed to the link?

[1]: https://i.stack.imgur.com/wIi95.png
samcarter
It seems like you just need your beamer frames in A4 format. You could use \usepackage[size=a4,scale=4.0]{beamerposter} to get A4 page size out of the box (the scale=4.0 factor was just chosen by eye to get similar font size, you can fine tune it if needed).


\documentclass[12pt]{beamer}

%\usepackage{float}
%\usepackage{amsmath}
%\usepackage{pgfpages}
%\pgfpagesuselayout{resize to}[a4paper,landscape]
\usefonttheme{professionalfonts} %To get the accents aligned correctly, albeit in Computer Modern Roman

\usepackage[
size=a4,
scale=4.0
]{beamerposter}

%\usepackage{hyperref}
\hypersetup{
%filecolor=magenta,
%urlcolor=cyan,
urlcolor=blue,
}

\setbeamertemplate{footline}
{
\leavevmode%
\hbox{%
\end{beamercolorbox}%
\end{beamercolorbox}%
\end{beamercolorbox}}%
\vskip0pt%
}

\title{Test}                % used by \maketitle
\author{John Doe }
\date{Spring 2020}                  % used by \maketitle
\institute{John Doe University}
\begin{document}
\setcounter{section}{5}
\maketitle                  % automatic title!
\begin{frame}
Click on this link: \href{https://ocw.mit.edu/courses/aeronautics-and-astronautics/16-323-principles-of-optimal-control-spring-2008/lecture-notes/lec5.pdf}{MIT OpenCourseWare, Page 5-18}
\end{frame}
\end{document}

Ulrike Fischer (imported from SE)
Don't use \pgfpagesuselayout{resize to}[a4paper,landscape] to resize the page. This moves the text but not the links. I enabled link borders and now you can see that the clickable area is not where you expect it to be:

[![enter image description here][1]][1]

Side remark: beamer already loads hyperref so there is no need to do it again.

[1]: https://i.stack.imgur.com/DOSoq.png

Enter question or answer id or url (and optionally further answer ids/urls from the same question) from

Separate each id/url with a space. No need to list your own answers; they will be imported automatically.