Not sure if this is the way it’s supposed to be. When I change the preference from clicking on groups will reveal the corkboard to revealing the contents in outliner view, then hit Apply or OK, nothing changes. If I click on another group, nothing changes. Then if I hit a text file then go back to a group, it changes. The same in reverse. It is consistent. I would expect the change to be immediate upon hitting Apply or OK.
This is intentional. The idea is that if you have entered corkboard mode, you will want to stay in it when you go to another group, regardless of your preferences. This way, if you decide that you want to view your groups in corkboard mode even though Preferences are set to outliner, you can navigate between groups to look at index cards easily without having to change your preferences.
Ah, I see. I guess it’s a little confusing only because I didn’t actually ‘enter’ corkboard mode, since it was the default. And I wanted to have it view in outliner by default, so I would have expected it to change when I changed it in preferences. Then I can see the logic if I actually select corkboard and then it stays while I view groups.
But now that I understand it, I can certainly adjust! 
Changing the preferences most certainly should not change the current viewing mode, only future changes.
I should have clarified. Sorry. I meant I expect to see the new preference with the next group I select. I don’t. It doesn’t change until I hit a text file. I wouldn’t expect it to change if I have a folder selected already. But I would with one I select next. That’s what I meant.
Right. But I think I have explained why that is. I would not want the behaviour you describe. The current behaviour allows you to navigate between groups whilst maintaining the current state you have selected - either outliner or corkboard - regardless of preferences. That way you can switch to either outliner or corkboard mode and use ctrl-up or down to navigate groups whilst staying in that mode. If I implemented the behaviour you describe, if your preferences were set to outliner but you decided you wanted to do some work on groups in corkboard mode, you would have to keep resetting it every time you navigated to a different group, which would be very annoying.
I see how it works a bit better after trying it out more. When you select the preference, the corkboard (or outliner) function actually toggles. So what you describe makes sense now. Sorry for my lack of programming skills. I didn’t put together that when you select a preference it’s the same as selecting the function via the toolbar button. I thought it set it at a deeper level or something (whatever that would be). I don’t know if that makes sense, but I understand how it works now, so I understand also why you have it the way you do. Thanks.