Hello Thomas,

If you want to update attachment info. you need follow this step.

1. Make sure activated developer mode. If you don't know how to activate developer mode here are two options.

    i) click on setting menu go to last option on dashboard click on activate developer

 or 

  ii) write on your browser directly web?debug=

These options will activate debug mode on your current browser tab.

2. Now go to following menu

      Setting>>Technical>>Database Structure>>Attachments

     This menu will take you to the documents. now you can play with document as you want

I hope this will help you a little.

Regards,

Anil.