Thanks for your question. I want to make sure I understand what you would like to do.
You wrote “change access files permissions“. Does that mean you want to change which Media Library items are visible to a group of users, e.g. users with a particular WordPress “role”?
If that’s what you mean, MLA uses the WordPress “Roles and Capabilities” API to control access to several MLA features. MLA tries to match the controls built in to the WordPress Media/Library screens and maintain compatibility with WordPress features.\
If you have found a specific problem or if I have not understood your question, any additional information you can provide will help me investigate further. Thanks for your interest in the plugin.