Musical key-changing apparatus for stringed instruments

A zither comprising:

• a. a zither case
• b. a plurality of strings with each string of said plurality of strings having a first predetermined length corresponding to a plurality of flattened musical notes, with said plurality of strings attached to said zither
• c. a spindle apparatus to set one of a plurality of key signatures onto said plurality of strings while maintaining a home identity of each individual said string of said plurality of strings in each of said plurality of key signatures, with said spindle of said spindle apparatus attached to said zither case near to and transverse to said plurality of strings in a plane parallel to said plurality of strings with said spindle at a first calculated distance from one set of ends of said plurality of strings for a first calculated length of strings corresponding to natural musical notes and with said spindle having a plurality of rotatable key signature positions, with said spindle for each said string in each said key signature position having in a first instance a first predetermined radius to contact and fret each said string of said plurality of strings at said first calculated length corresponding to a natural note when said one of said plurality of key signatures requires said natural note for said string
• d. said spindle apparatus to further include a sharp fret transverse and near to said plurality of strings, with said plurality of strings sandwiched between said sharp fret and said spindle, and with said spindle for each said string in each said key signature position having in a second instance, when said one of said plurality of key signatures requires a sharp note for said string, a second predetermined radius to push said string against said sharp fret with said sharp fret at a second calculated distance from said one set of ends of said plurality of strings consistent with a second calculated length of said string corresponding to said sharp note in said second instance.