Icons are often times confusing, especially on dialogs you may not use everyday. One such place is the Volumes. On the palette there is a buttons to export and import volume entries from/to a file.
The buttons are easy to use. Use the export button to create an XML file to reflect your volume entries, and then use the Import button to bring them back in. This way you won’t have to recreate them each time you open a file. If you are standardized on the names of surfaces, you can use the XML file for all of your files.