(idiomatic) To convert to, to make a transition from one system to another.
Change-over Sentence Examples
Thus cementite is always tending to change over into graphite by the reaction Fe C = 3Fe +Gr, though this tendency is often held in check by different causes; but graphite never changes back directly into cementite, at least according to our present theory.
For example, sulphur is stable in the rhombic form till 95.4°, from then upwards it tends to change over into the prismatic form.
She'd become so accustomed to the British Roadster, and now had to change over to a VW Golf convertible.