Persistent change of caption width in memoir

Question

How do you persistently change caption width in memoir? I know you can use \changecaptionwidth followed by a \captionwidth{...}, but that only works within a float and I don't want to have to specify that all the time.

Also, if caption widths can be set persistently, how do you revert to using the full width when using subcaptions?

Answer 1

At least for me, \changecaptionwidth does work in the document preamble.

\documentclass{memoir}

\newcommand*{\sometext}{Lorem ipsum dolor sit amet, consectetuer
    adipiscing elit. Ut purus elit, vestibulum ut, placerat ac,
    adipiscing vitae, felis. Curabitur dictum gravida mauris.}

\changecaptionwidth
\captionwidth{0.6\textwidth}

\setfloatadjustment{figure}{\centering}

\begin{document}

\begin{figure}
\rule{1cm}{1cm}
\caption{\sometext}
\end{figure}

\normalcaptionwidth

\begin{figure}
\rule{1cm}{1cm}
\caption{\sometext}
\end{figure}

\changecaptionwidth

\begin{figure}
\rule{1cm}{1cm}
\caption{\sometext}
\end{figure}

\end{document}