Attach file only visible to all users

I have a attachment field which is only visible to one user , when i set permissions as private and upload it displays on the sidebar attachments, i dont want other users to be able to view or download the documents.

The attach file will appear, if you have added the attach file and if the attach file is private then you will be able to download it, no one else will be able to download it. But if the other user can see the attachment, they will not be able to download it.

he issue i am facing right now is

USER 1 Uploads and sets document private , the file shows on the sidebar attachments with a lock symbol

USER 2 can see the attachment and when user 2 clicks the attachment with the lock symbol the user is able to download it.

why is this happening ?

should i change any settings or permissions ?

Please apply and check it.

hey i have added the screenshot of my settings and permissions,

I am not able to delete the file but i am still able to download, view the file from user 2 that user 1 uploads.

should i apply this settings to the doctype as well ?

I believe there is a bug where clicking the lock button prevents the file from being opened, but clicking the link allows for an easy download by the user.

how do i fix this ?
is there a alternative solution or a workaround it ?