Hello,
There is no feature for this in the plugin. You would need to set each sermon post’s featured image manually (you can select the uploaded image without needing to re-upload) or make a modification to accomplish what you’d like. Or, see if there is a plugin that can help in some way.
I may in the future add an option to set an image on each series taxonomy term but there is nothing like that right now. WordPress did not until that last update allow meta data to be set on taxonomy terms, so now there is that possibility.
Please let me know if you have any questions.
