Having Difficulty Centering Text In A Text Box (Menu Doesn't Appear)

Hello any and all who may be able to help me fix this issue. I'm in the process of trying to center some text in a text box but the text box menu bar that usually appears at the top of the box whenever I attempt to edit it has mysteriously vanished so I'm unable to center my text properly. I've included photographic evidence of the issue in order to more accurately highlight the issue.

My website is located at: opossum-koi-3j8g.squarespace.com/config/

Or the public version: weekendmovienightreviews.com

Thank you to anyone who can help me in advance.