I just noticed a new feature on Dropbox (version 51.4.66) on my Mac - I deleted a folder inside my Dropbox folder (moved it to the trash) and I was presented with a dialog asking me if I wanted to delete the file just from the computer I was using, or from everywhere. There was a checkbox next to "Don't show this again". I checked that box, but on reflection I would like to see that warning when I delete files. So how can I re-enable that warning on my Mac?