
Once text is added to $Text, its style—at time of entry—is saved in the TDF data and so it is unaffected by subsequent changes to $TextColor. Re reset a note's $Text to use a (new) $Text colour, select all $Text—or that to be repaired—and use menu Format ▸ Style ▸ Standard Font. (N.B.there must be a $Text selection for this to work)
To re-colour (selections of) existing $Text, i.e. to a colour different from $TextColor, use either the Format ▸ Style or Format ▸ Font menus.
See also—notes linking to here: