adding image preview doesn’t work anymore

I added several Youtube Widgets Responsive and they were all working, then I decided adding preview images to all the widgets and there were any trouble until the last two. After a lot of attempts one now is working, but for the last one there is no way: now, if I try to add a new Youtube Widget Responsive I can’t set it at all…
Obviously, I tried to delete and reinstall the plugin, clear the cache and so on, but anything worked… I’m really disappointed because in the future I would like to add other Youtube Widgets Responsive but if they don’t work…

• This topic was modified 6 years, 10 months ago by setleo.

The page I need help with: [log in to see the link]