Hi I just made a post with a .gif image attachment. I realised I had attached the wrong image and went into edit and selected "replace attachment".

This changed the NAME of the attachment to the correct one, but the contents remained the same. I then re-edited, deleted the attachment, returned to the post, edited again with the correct attachment and returned to the post. Once again, the name was correct, but the original (incorrect) image was displayed.

I had to resort to copying the post, deleting it then re-posting it and adding the correct image.

That worked