My "x" button has disappeared from my tabs. How do I get it back?

Until recently, when using multiple tabs, I would have a close button or "x" in every tab. I did not make any changes to settings, but now, my close tab button is gone or at least not visible. Currently, the only way I can close individual tabs it by right clicking on the tab and selecting "close tab". It would be much easier if my button was back and functioning. Please help me fix this...