I understand that your interface was built over a long period of time, with a lot of input and testing. I think I may have a really easy solution to address this. Can you simply *change* the label of the button? For example, when you are viewing ‘My Sessions’ the label says ‘All Sessions’, such that it is obvious what action that button performs. Even better, could you add a verb to the label? ‘View My Sessions’, ‘View All Sessions’ ? That would be an easy solution I hope.
Again, thanks for your help