In our voiceover studio I still use Sonar 8.5.  Yea, I know it's archaic (I use SPLAT in my music production suite) but it's ultra stable and configured for what is done in that room.  The problem is I'm so used to doing only what I do in that room that I've forgotten almost everything else about 8.5 as in the other suites we've continued to upgrade through all the versions including the latest Platinum.  In any case...I have accidentally hit some key or other which has caused a condition that's driving me nuts.
 
I am constantly cutting up and slamming together bits of voiceover and music and sound effects and heretofore if I pushed to clips together they just "meshed" with each staying intact.  But now, if I let two different clips actually touch or encroach on one another a crossfade appears in both clips and even stays if I separate them again.  In some cases I have to undo several moves to make these crossfades go away.
 
So...what key or keys did I hit and how do I undo this?  
 
Pardon my tedious ignorance.  I am at your mercy.
 
Thanks.
 

 
 
Not sure what your keyboard shortcut was Ol'Pal, but I think this is how you resolve your problem.
 
Options > Global > Editing and uncheck Crossfade Audio Clips upon overlap:
 

Thanks so much Straummy!! Will give this a try. Much appreciated.

There's also a Crossfade toggle button that you might have hit:
 

That's probably what did it.  In the voiceover studio I never use them.  Probably accidentally hit it and then misery ensued.
 
 

yorolpal
and then misery ensued.

Like this?
https://www.youtube.com/watch?v=j_aoWTNdHwY