*Note: You may need to go to Folder Options/ View and select Show hidden files,folder and drives. AppData is hidden by default.
Or, you can get there by simply clicking "open desktop data folder" in DX Config. Delete what is in there.
But, the one you made is stored where? DX should be loading it. Did you save your changes? Did you modify the one that keeps loading and forget to save changes?
That still shouldn't cause what is happening. Unless you loaded another without saving changes.
Whenever you either alter an existing theme, or make your own, you must save your changes.
What version of DX?