Thanks but the issue is that the user is logging in and then the credentials are being stored by the powerapps app. We've never allowed anonymous users.
Better explanation is this:
User opens powerapps app on the iPhone.
They are asked to sign in.
They sign in and are able to see the assigned app
They do the work in the app and when they are done, they save and this will automatically log them out and close the app
Next time they open the app, they will again be asked to sign in. This time they will see their credentials from earlier and be able to select them and be automatically logged into the app without entering their password.
When they hand the phone off to the next user, they will be able to login with the credentials from the earlier user. This is all within the powerapp app.