It was brought to my attention by Ed Hrebec (of Spirit of the Woods Flutes fame) that the distinction between uploading a personal photo vs. an avatar was unclear.

Your personal photo is what appears in your user profile.

If you want your picture to appear at the top of your posts, you need to use the avatar settings section of your control panel.
On the left hand side of the page (on your control panel) you will see an option to "Edit Avatar settings". That will take you to the section where you can choose an avatar (or upload an image from your computer).