Thank you for playing, and for the insight into your experience!
Our original idea was that the player wouldn't be holding the resizing-gun at the start of the game, and that they'd pick it up from a pedestal atop that first platform. That way, the wooden crate would act as a tutorial for pushing objects, before you gain the ability to resize things.
The scale/seesaw room tries to teach the player two concepts at the same time due to time constraints, so that's likely where the confusion comes from. It requires the player to go back and obtain mass from the previous room, using it to make the box significantly larger and heavier. But it also presents the player with a more complex physics problem, where they must use leverage to tip the wooden plank.
A mechanic to pick up smaller boxes is something we'd like to explore, if we take this game idea farther.
Thanks again for the feedback!