Hi @Suelue,
Greetings from the Roku Community and thanks for the inquiry!
At the moment, each picture is shown for ten seconds, and the stream loops in a random sequence. We don't have any information to give on this, but you can check out the most recent news and updates on our blog at Roku Blog.
You can also refer to this support article here on how to use Photo Streams on your Roku streaming device.
If there's anything else that we can do to assist you, please let us know.
Best regards,
John
John
Roku Community Moderator