When you change the style of note heads, whether it is for shape notes or solfege note-heads, you can now select if the style is applied on a fixed-do or a movable-do basis.
Fixed-Do
With the fixed-do, the color/shape used with a note will only depends on its pitch. A G will always be displayed with a So in Fixed-do.
Movable Do
With the movable-do, the color/shape used with a note will depend on the note pitch and the key signature's tonic. A G with a G major key signature will be displayed with a Do in movable do.
You will find this option at the bottom of the note style configuration page.
You can find all the information related to the styles of note heads on our dedicated help page.