Under the Tools menu is a File Security entry with which you can change permissions for files and folders.
This function requires Administarator permission to operate, so you may need to run Multi Commander as an Administrator.
The File Security submenu provides the following options:
Allows you become the owner of the selected files and folders.
Remove all permissions
This removes permissions for all users and groups from the selected files and folders. Note: no-one will have access to the files after this change. Use the Add Permissions command to add permission for yourself and/or others if needed.
This adds permissions for users to the selected files and folders. You can easily add read-only access or read/write or full-control.
If you want to give everyone access to a file/folder you can add read/write or full-control access to the group Everyone for the selected files/folders.