While trying to understand a mistake in a recent print I've just realised one likely cause. I'd been assuming that after changing parameters (such as length, width, etc) in the Customizer panel of OpenSCAD (and previewing and rendering), that the code would also change too. But that's clearly not the case on closer study.

Which explains why I was dismayed to find, the day after using File > Save, that I had lost my previous edits.

That seems a very basic design flaw to me? But as a beginner with both 3D printing and OpenSCAD I'm curious to know what others think please?

My tentative conclusion is that despite the simplicity of using the Customizer, I'll make all my changes in the code in future.