Persistent change of caption width in memoir

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?

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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}

\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}

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Huh. Now that I retry it, it works for me too; before I got a compilation error. Must have been after I fixed the memoir-caption conflicts after removing the subfig package. –  gablin Sep 18 '11 at 16:51
If you face an error, always try to delete auxiliary files and then compile again. –  lockstep Sep 18 '11 at 16:53