v9.3.1 - In changing colors, what does "Set Defaults" mean?

[johndee]

TPv9.3.1 installed, Windows-11, also have TPv4.7 installed.

When changing document-class colors, there is a button caption "Set Defaults".
What does this actually "do"?
I could not find it in the Help portion of TPv9.3.1 nor in TPv4.7.

I pressed it once, as I was changing the colors individually per document-class, and it changed ALL class colors to the "out-of-box/initial" colors.
I then had to re-enter all of the color values AGAIN for each of the document-classes.