How to stop Photoshop from centering image on canvas when exporting?

I am trying to export an image to use for an animation in png format. I need the actor's body to stay in the same place on the canvas. When I export the image from Photoshop it automatically centers the image on the canvas. How do I stop photoshop centering and fitting canvas to size. This is extremely easy to do with GIMP, so I'm confused why Photoshop is making it so difficult.

I'm using a Mac.

Thanks in advance.