Hi Joel,
After you change the value manually, choose from the Volume Viewer menu: Features… save default dialog settings.  That will save it as "your" default.  Just make sure you haven't changed other things to values you don't want as defaults.

<http://www.rbvi.ucsf.edu/chimera/docs/ContributedSoftware/volumeviewer/framevolumeviewer.html>
<http://www.rbvi.ucsf.edu/chimera/docs/ContributedSoftware/volumeviewer/volumeviewer.html#features>

I hope this helps,
Elaine
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Elaine C. Meng, Ph.D.
UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab
Department of Pharmaceutical Chemistry
University of California, San Francisco

On Nov 18, 2013, at 7:20 AM, Joel Meyerson <meyersonj@mail.nih.gov> wrote:

> Hi,
> By default, Chimera displays up to 3 histograms in the "Volume Viewer". I know that this number can be increased manually in the "Data display options" after launching the program, but I would like to change the default number. Is there a built-in Chimera preference to set the default number to something higher? If not, can you perhaps suggest how this might be scripted to happen upon launching the program?
> Thanks,
> Joel