Each theme (.THMX file extension) includes one color scheme, one font set, and one effects scheme. You can edit the color scheme and font set in the PowerPoint interface and save the theme. The new color scheme and font set will travel with the theme.
If you create more than one new color scheme or font set in the PowerPoint interface and expect them to be included with the theme when you save it, you will be unpleasantly surprised. These additional schemes will not travel with the theme; they will only be available on your computer.
If you want these additional color schemes to “travel” with the theme, you must add the color scheme by editing the XML manually.
You must modify the theme’s XML code in order to add these color schemes.
If you want a color scheme to always show up in a user’s “Custom” area in the Design tab Colors dropdown, then add the color scheme XML to
C:\\Users\UserName\AppData\Roaming\Microsoft\Templates\Document Themes\Theme Colors (Windows Vista) or
C:\\Documents and Settings\UserName\Appliction Data\Microsoft\Templates\Document Themes\Theme Colors (Windows XP)