How do I get back to a split view?

I feel silly posting this, and I’m not sure my terminology is right, but I can’t figure out how I messed up or how to fix it. Until recently, when I typed a post, the field was split, with what I was typing showing on the left side and what the post would look like when it appeared on the boards on the right. Then suddenly, the right side disappeared, and now I can only see what I’m typing. Anybody else experience this? Did I hit something accidentally? How do I get it back to the old split format?

Click the double sideways caret at the bottom right corner of the text window.

Stranger

I get the split view automatically on my desktop or tablet and the single reply box only on my phone.

If you attempt a reply, click on the icon on the bottom right (a tv screen?) and you’ll see the other screen.

Thank you both! All fixed!