If I add a new form to my original form, the new form appears dark gray or black, as compared to the original form, which appears light gray. What does this signify, and how can I get the entire form to appear the same light gray?
It means it does not yet have a material applied.
When you add a material scroll down to the settings panel and you will see “Viewport color”, This is what defines the ‘light grey color’ you are seeing