So that's not the cause of the problems... :(

It is normal to see the locks in the frontend but not in the backend.
Have you set any user permissions for your groups?

No, I use the default settings. And I changed nothing... :(

I usually use the backoffice to send the articles, and in the backoffice

I am not sure I follow you... Do you mean the backend?


It is normal to see the locks in the frontend and if I understood correctly in the backend you do not see any locks, right?

I am not sure I follow you... Do you mean the backend?


It is normal to see the locks in the frontend and if I understood correctly in the backend you do not see any locks, right?

yes and yes

thanks

So you only see locks in the frontend.

This is normal behaviour and takes us back to the post by Yiota

The lock appears in the frontend of the K2 Media Manager because the permissions are limited by default. All users can use images that pre-exist in the server but they do not have any access to add/edit/delete files or folders through the frontend.
This is a measure K2 team has taken in order to secure the server's files/folders.

To add new images you can try doing it from your editor.