That's because you cannot edit the EQ of the style parts or voices separately.
That's what I thought Gary after searching and knowing the
Yamaha S-series units, etc, OS for years ...
cut backs in different models have to be made somewhere.
no biggie there are other workarounds when needed & most of my styles were customized on all my S units long ago..
That said I gotta say the S670 is the best bang for the buck
in an arranger KB. There is so much S970 inside that makes it a super efficient keyboard for sure...who knew?