Can’t get rid of annoying white space on left-hand side of my posts

’ve tried fixing this for hours and it’s just annoying me at this stage so I’d love somebody’s help.

I’m using the default WordPress 2016 theme.
My site is http://www.brainhackreviews.com

As you can see, the home page looks fine. But when I actually make a post, the text inside the main body of the post keeps aligning to the right. I have it set to align left in the formatting options, but it’s not working.

See this post for an example of what I’m talking about -> http://brainhackreviews.com/alpha-brain-review-a-wonderful-supplement-for-improving-focus/

How the heck do I get the text over to the left-hand side of the post? I’ve tried absolutely everything including modifying CSS code. When I log in to the Dashboard, the white space on the left is actually taken up by an edit button. So I’m assuming there’s some kind of toolbar there.

Could somebody more intelligent than me please help? I’m a perfectionist and this issue hurts my eyes.