OK silly question...
 
In Track View sometimes when i grab the bottom of a track that is not high-lighted all the tracks open like an accordion- following what i do to one track.  In some files track view acts like it use to...just the track I grab to open- opens up.
 
I know this is a fairly recent update,  I wasn't paying attention.  Is there a button that turns this option on and off? I'm assuming that is the reason why it works in some files and not others, I'm accidentally toggling it on and off.
 
 

This is not that new of a feature. It's called  'Auto Track View'    View/Auto Track View=Shortcut is Shift+Z
A good indicator to see where you stand on  track zooming is this:
If there is a little 'double arrow' just to the left of the meter, at the top, you can expand individual tracks.
If the double arrow is not there, you will be in Auto Track View, and able to expand all track heights.
 
Michael
 
 

Yes, and it drove some people crazy at first. But what's so cool about it is if you have a project with a ton of tracks, they can all be collapsed but when you want to see one in detail, click on it and poof - it becomes nice and big.

THANK YOU GUYS....yes I could see how it could be a cool thing, but I could not figure how to control the feature.  I knew i was toggling it on and off some how.  I just worked around it all the time.  Wishing for it sometimes and frustrated when it happened when I did not want it.
 
THANKS