The previous pop up 'Voice Info' function has been replaced on the SX models (and Genos) with a series of icons above the voice name of each applicable voice type on the Voice Part Setup display (open by pressing MENU > Voice Part Setup).
The meaning of each icon is described on page 32 & 33 of the SX 'Reference Manual' (not the Owner's Manual!) which you can download from your local Yamaha Support website.
This should allow you to 'decode' the icons shown against a particular voice, although in my opinion, it is not as clear as the previous Voice Info text function.
Regards
Ian