You cannot edit a default style like [None].
just add a new style then you can give it characteristics.
[None] is a character style and as previously stated, can't be redefined. It's used to remove a character styles that have already been assigned.
Normally, we set up our paragraph styles first, and then apply character styles to emphasize or differentiate text strings within a paragraph. But you can redefine the look of [Basic Paragraph], which may well take you where you want to go.
Do you see the difference between Character and Paragraph Styles? Any Paragraph is formatted with a Paragraph Style. You can format it by overriding it manually, but I would not recommend to do so. Work with properly defined Paragraph Styles. Character Styles define a local different formatting, either in Graphic attributes (font, size, color, etc.) or some underlaying property which is different from the hosting paragraph (language, direction, etc.)
Use Paragraph Styles on the first place, not Character Styles. [None] in the Character Style Panel removes all applied Character Styles to the default settings of the used Paragraph Style.
Build up you document with several Paragraph Styles.