In a recent presentation we did, we added a lot of long notes…
At the specific document we had changed the aspect ratio to 16:9 using the following documentclass.
%[aspectratio=169] changes aspect ratio for slides from 4:3 to 16:9, should be better with columns
\documentclass[aspectratio=169]{beamer}
When we compiled the presentation showing the notes on the second screen, we noticed that the notes were not utilizing all of the white space. There was a huge empty column to the right, most probably it was the space that was added after changing the aspect ratio from 4:3 to 16:9.
The template we were using for the notes page was plain. To fix this issue we used the following commands to create a new version for the plain template, called wideplain.
\makeatletter
\defbeamertemplate{note page}{wideplain}{
\vskip.25em
\nointerlineskip
\begin{minipage}{.9\paperwidth}
\insertnote
\end{minipage}
}
\makeatother
After we used this new template, the notes became wider and they used all of the available space.
%Enable to produce notes
\usepackage{pgfpages}
\setbeameroption{show notes on second screen=right}
\setbeamertemplate{note page}[wideplain]
Note:
In the code we defined the new template, initially we used \textwidth instead of \paperwidth which resulted in the same result as the plain template. So we assume that there is an issue somewhere that the notes template does not adapt its \textwidth properly when changing the paper aspect ratio.