I am just learning about creating customized themes. Select one item of the new object. Can't save while there is more than one selected. Then save it either to default or a special name.
Then with no one object selected click on the drop down by the theme name. Save it to the theme. When that is done it should "flow" to all common items.
I hope that helps.
Yes! when I followed those steps it saved my new theme.
Thanks so much.