I am a member of several (private) ArcGIS Online Organization. I was given a link to a StoryMap recently and I have no idea which Organizational site I need to sign in to. Basically I have to try each one to find out which Organizational site this StoryMap belonged to.
Sure, whoever sent me the link could have provided that information, but should they need to? And if they only belong to one organizational site then they may not even realize we have multiple within the company. Also we engage with a wide variety of users with different levels of experience with ArcGIS Online.
When you launch a StoryMap from a link and you need to sign in, there should be some prompt or indication as to which Organization you need to sign in to.
This link to a StoryMap takes you to the generic ArcGIS Online sign in: