There are three different types of streams: 

1-on-1s: These are only visible to the two people involved
Private: Visible only to you
Shared: Visible to whoever it has been shared with

For the shared streams, you will be able to see the number of people you have shared the stream with at the top represented by a number. 

And by clicking on that number, you can see the names of the people who can edit the stream. 

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