If I change the font in the standard style with Format Styles, the edit cells change but the rich edit cells do not. Can you explain this?

The rich edit control does not support inheriting attributes (font, text alignment) which need to be stored directly into RTFstring. You have to call SetStyleRange() explicitly for each RichEditCell.

Example:

   SetStyleRange(CGXRange(1,1,GetRowCount(), GetColCount()),
      CGXStyle().SetFont(....).SetHorizontalAlignment(...));

All other attributes like background color can be applied by changing the standard-style.

If you only have a few rich edit cells you might also loop through the cells and call SetStyleRange only for rich edit cells and change all other cells via StandardStyle().