Why are all users' files visible to everyone!

I have a new My Cloud EX2 Ultra. It’s installed on my desktop PC running Windows 10. I’ve set it up (had some problems because the setup didn’t recognise the device, but got there in the end). I’ve made it fixed IP and made sure the admin account has a password. Now I’ve added three users (the desktop PC is used by all the family), each has set-up its own password, but when you login as any of those users, you see everyones folders and files! This applies to the mobile app as well.
Regardless of who is logged in, they can see (and do things with) everyones files! How do I make it secure?
Update to this: When I login under the email associated with the admin account, I don’t get the options I should as an administrator according to the User Manual (Sect 5, p20-21), so something is not right there. I don’t see a “navigation bar”. I just see the icon top left and if I click on the settings cog I just get a small popup screen showing “Devices” and single option to “Manage Users”, which doesn’t show the information described under “Viewing Users” on p20 of User Manual. I’d upload screen grabs but as a new user it won’t let me!

If you sign in as administrator and then go to the users tab on the GUI interface, you should be able to turn on/off access to each of the shared folders for each different user so they can only see their own folder of files. See screen shot below.
In this screenshot you are looking User # 3’s access and you can see that they have full read/write access to their own folder and read only access for the Plex folder. All other folders (especially for others users) is turned OFF so they would not be able to see other user files… Make sure you go into each users profile to get to this screen and turn on/off shares as needed.
The Admin account should have everything ON of course

BTW: I changed the user names to protect the innocment ;p
Hope you can work it out

Hi kinglerxt and thank you for responding. My problem (it turned out) was I hadn’t worked out how to get to the Dashboard. I had only got to a screen that allowed me to add or delete users, but not modify them in any way. I had got myself into a terrible muddle with device usernames, shares and individual users and passwords… Once on the Dashboard (which I have now saved as a favourite!) I have managed to set things up correctly. Well, almost correctly. I have set up 4 users (including the admin one) and 3 of them work fine. But for some reason, one user refuses to accept the password I set for it. I changed the password but it still didn’t work. It displays an error saying “Multiple connections to a server or a shared resource by the same user, using more than one username, are not allowed…” I don’t think I understand the difference between a “user” and a “username”? What is a “user” in this context?

a user would be what the NAS sees as a person/user. A username can be anything you want to call them like Joe or Nancy or Linda, or if you want to remain annonymous, kinglerxt or salsaguy if you want to use screennames instead.
Glad you were able to work it out mostly
Good luck