Restrict user-role editor to only see own media files in library

Hi guys :slight_smile: - I really hope someone can help me out here, as I'm having a huge problem:

I've created a site, where I have a lot of users set as "Editors", in order for them to do stuff around the site.
Even so, I badly need a snippet of code, to limit those Editors (when uploading/editing own media into their own posts) from being able to see other people's/other editors uploaded media in the library. Their posts are mainly created through custom post types...
I've been searching the net for a snippet of code to insert into my functions.php and have found a few (about 4 different) - but have not been able to make any of them work as intended.
Most likely it is due to my own limited capabilities that they don't work, but never the less I really hope someone here can help me on my way.
Also, I have tried differet "user-role-management" plugins, but either I mangage for them (the editors) not even be able to edit their own posts - or they can still see all media in the library - including what is not theirs.

Should say that even if I can stuff snippets into functions.php, I do not know neither PHP npr jQuery as such... So please bear with me :slight_smile: