It is a two-step process. Save the style of the selected item. Deselect all objects and then save the theme. When you do that it should fix your problem. I love having my own them. I created one for display screens and one for printed reports.
Instead of using the field picker, you can also Ctrl drag a field with the format you like, the change the field reference. You can also use smart duplicate key strokes to make multiple fields quickly. Seems quicker to me then dragging the field picker. Same for labels-Ctrl drag, dbl click, type.
Thanks, TKnTexas. Unfortunately that did not work for me. Even after setting the default field and label formatting in, for example, the Header, all new fields placed there keep having white text. Thank goodness for the Format Painter. :-)
Thanks, Steve. That would be quicker if I had just a few fields.