Use a simple reading size
Set the output size for the visual role of the equation in the slide. Use the preview to check hierarchy before you export.
Choose predictable placement
Use Standard PNG when the destination app needs an image that places predictably. Use SVG when the design tool preserves the vector dimensions you need.
Keep the source nearby
Copy the LaTeX too if you expect to revise the equation later. Version 1 does not keep a document after you close the app.