By default, lettering objects are filled with Satin stitch. You can apply other fill stitch types such as Tatami or Program Split as well as stitch effects such as Jagged Edge. See Stitch Types for details.
Note: Lettering values are stored in the <PRESET_LETTERING> style in the Normal template. Changing these does not affect the values of other objects. Do not delete or rename this style. See Working with styles for details.