Accidentally discovered the extend page feature and how there isn't a way to revert to the original page size of a Lumio lesson. Currently there are 4x3, 16x9, and 16x9 large.

Opening an existing Lumio lesson has none of these sizes originally selected and extending the page sets it to 16x9 large. Setting it to 16x9 still leaves a substantial amount of white space around the page, showing it isn't the original page size.

Would be great to have a fourth option for the size a Lumio lesson is set to.