I think I've solved the doubling up of the Demo themes, but I'm still struggling with the issue of plugins in conflict with the galleries. Here's the message I'm getting:

Jetpack's Carousel has been disabled, because another plugin or your theme is overriding the [gallery] shortcode.

I'm seeking to use the Soledad Theme, and decided to work from one of the Demo themes, Fashion and LIfestyle, for this site. When that theme proved not quite right, I switched to another one, Photographie, but when I loaded the theme, I ended up with elements of both themes on the site. I uninstalled the Soledad theme, and then reinstalled in with a very simple them, But all three themes now seems to be combined on the site. I uninstalled again and tried to use just the original Soledad theme, but the site is still a mess with all sorts of themes combined.

Also, I'm getting an error messages that says an existing carosel is in conflict with elements of the new them, so I'm not getting any gallery pictures to show.