Thank you very much! I contacted the hosting services of the website and apparently there was a problem with the rights of the folders.
Now it is working fine.
Thank you very much again for your help!!
Dear Yop Team,
With a huge delay, thank you very much for your help. I was all this time trying to find out how my wordpress theme works and to change its css file, since I realized this was an issue of the theme and not the plugin (I installed another plugin for the contact information and still got the same). Actually, I didn’t manage to finally change these settings, but I think I can live with it 🙂
Thanks a lot in any case for your help and time! The plugin itself works very nicely!