Settings where? On the screen itself? What you are producing?
Here's the thing. You have posted and in effect done the following. You wandered into a health clinic and just blurted out you don't feel well. And just as if you had done this, much more information is needed.
You said you made a video. Okay, how did you make the video? Did you record it using Camtasia? Did you record it using Jing? Did you record it using SnagIt? Something else entirely?
You said you used "default settings". Again, this isn't exactly clear and may differ depending on the product you used. We would need to know more about what the "default settings" that were used actually are.
You said it's not playing back on a horizontal screen. Again, what kind of screen? A phone held in landscape mode? A TV? A Monitor? A screen on a cash register? What screen? And does it play back just fine on a vertical screen? If so, what kind?
Once you more clearly articulate the issue and the environment, perhaps someone hanging out here can better assist.