Hello @fillinlight,

First of all thank you very much for using the pro version of the theme.

Now, the feature slider in the theme can be set using page, post, categories, tag etc.

If you are willing to use the pages then to change the image in featured slider you need to go to individual page edit screen and change the image in Feature Image section.

http://prntscr.com/k1gitp

But if you want to set the slider using the post, categories, tags then you have to go to individual post edit screen and change the image.

Screenshot:

http://prntscr.com/k1gjb2

Hope this helps.

If you have any confusion further then please let us know.

Thank you.

Best Regards!!