Whenever a custom stream is created, it is unique to the dashboard user that created it - until they choose to share it with other dashboard users on the account.
Sharing the stream is very easy.
Click on the drop down button towards the top right corner.
Then select "share stream" from the drop down.
Alternatively, you can can access the SHARE screen from within the streams dashboard.
From the streams list, find the one that you wish to share and click the blue icon.
Check the box next to the name of the people you wish to share the stream with, then click SHARE in the bottom right hand corner. Your stream will now become visible to these people.