Center stage and remove borders missing

I have Adobe Animate 2018 since last year, since I downloaded until recently, there were three buttons at the top right corner of the stage; one was for centering on the stage, one was to remove the background and everything else that is not on stage, and I don't remember the other. Suddenly, last month these three buttons disappeared and I can't get them back, not even resetting the work space. How do I get them back now????

The red square is where the buttons were supposed to be but are not.