What I noticed with the browsers is that they keep making changes.Most monitor screens are bigger than what I got, I cannot even buy my current monitor because no one makes it anymore, lol.
Those buttons probably did not disappear, they might not be able to fit onto the screen.
Try that first is the only thing I can think of. Adjust the screen size of the browser or the monitor so that everything can fit onto the screen.
Next would be to poke around in settings.
Hope it works.