Instagram introduced a new feature in September 2018 that lets you share with other users stories via Instagram Direct, the app's private messaging tools for solo and group messages. The problem is that it works in both ways, so when you add your ephemeral story, anyone who sees it can share it directly with someone else.
When you look at your Story on Instagram, they see the Direct (a paper fly) icon that they can tap to share your story with one person, multiple people or a group. So a lot of Instagram users who are not following you can see your story, and there is no indication that someone has shared your story with the non-followers.
On the plus side, your story in Direct messages only lasts as long as your story lasts, so when your story disappears, nobody will be able to see it in instant messages. But if you do not want them to see it at all, you can easily disable the feature in Instagram settings on Android or iPhone.
: Go to Privacy and Security
Start by going to your Instagram profile page in the Android or iOS app. Tap the three-point menu in the top right corner, which will provide multiple options in a sidebar. You want to press "Settings" all the way at the bottom. On the following pages Settings (Android) or Alternatives (iOS), if you're on Android, touch "Privacy and Security." For IOS users, look for the section Confidentiality and Security .