Why are my Acrobat DC PDFs opening in Maximized full screen all of a sudden?

[Kristine Dahms]

Why are my PDF files all of a sudden opening up full screen / maximized view?
When I first click to open them, all that's visible is the thin title header, as if the window's collapsed, with the red/yellow/green buttons on the left but the document not showing.

When I click the green button to view the document, it automatically goes to full screen/maximized view and the only way out is to press Escape

and I'm back to where I started.

I googled and there seems to be a long thread from 2013 thru 2015 but nothing current.

Driving me nuts! Any help much appreciated. Thanks in advance.

[Pariah Burke]

Can you post a screenshot? Are you on Mac or Windows?

[Kristine Dahms]

Thanks for replying, Pariah.
I'm Mac OS Sierra.
I was wondering if I could post a screen shot... I don't see where how to attach to the message though....

[Kristine Dahms]

and here's what I get when I press the green button on the PDF header to open the document ( which I never had to do previously, it just automatically opened at 100% size, but not in maximized screen mode.

Also, Acrobat just crashed, coincidentally.

I checked my Creative Suite and looks like I have the most current version.

[Kristine Dahms]

Found where to upload screen shot