Which aspect of a scene can NOT be customized in the Scene Properties panel?

In the Scene Properties panel, the customization options are primarily concerned with the technical and visual setup of the scene itself. Frame rate, background color, and scene duration can all be specifically adjusted to suit the requirements of the project.

Frame rate determines how many frames are displayed per second, which is crucial for controlling the speed and flow of animation. The background color allows for the visual environment of the scene to be tailored, enhancing the aesthetic direction. Scene duration establishes how long the scene will play out in the timeline, which is important for pacing.

In contrast, character movements occur within the timeline and are typically manipulated using keyframes, animation tools, and rigging features rather than through the Scene Properties panel. These adjustments involve individual animated elements and require a different set of controls. Thus, movements of characters are not a customizable aspect within the Scene Properties panel itself.