Is it possible to change the shape of the panels after they are finished?

On MediBang Paint (desktop version) you can enlarge/reduce the size of panels, or transform and move them by clicking on the arrow-shaped icon at the top of the Divide tool and selecting the panel materials you want to edit.

On tablets and phones, the icon looks like this.

iPad:

iPhone:

Android:

For iPad and Android, the Arrow tool is located to the side of the Divide tool at the top right of the screen.

For iPhone, you need to open the toolbar at the top left of the screen to select the Operation tool.