The demo image cannot be removed from the lightbox

I have a problem that I cannot solve. I am new to Weblow. I bought a template and I have a problem with the lightbox, I replaced the original images in the gallery and added my own. However, when the thumbnail is turned on to show media, the old demo photo still appears as the last image. It’s happening on every single lightbox I’m using. I have it in all the pages of the gallery.

Before sending the message I saw that someone had the same problem but I have not found the solution.

Thanks in advance!

Here is my read-only site