What I meant is that if the user chooses to use the "Manage Attachments" button in the "Additional Options" block in the advanced editor, then that user must choose to insert the image inline, otherwise it will show in the attachments box beneath the post content.
The user isn't forced to do this, but if the image is to be displayed inline, then that's what they have to do.
I instruct my users to use the "Insert Image" button in the toolbar instead, as images attached (uploaded from their local media) will automatically be attached inline.
Because of the inherent difficulty in this process, I wind up "fixing" a lot of posts. Unless an image is attached inline, it won't show up in the "Topic Review" and sometimes being able to see an image is critical for replying to the post.
I have one user who refuses to attach images correctly (he also refuses to use LaTeX), saying it's just too difficult on his phone, and whiny, lazy mobile users are at the top of my "poop" list.