To save a custom theme:
Open the project that uses the theme you have customized.
Choose File > “Save Theme as Favorite” and type a name for the theme.
Select the “Shared for all users” checkbox if you want other users of your computer to be able to use your theme.
Select the “Replace existing” checkbox if you want your theme to overwrite the existing theme you based your custom theme on.
The original theme will no longer be available.
Click OK.