EVOLUTION is a demonstrably changable theory: proposed, written, re-written, organized by committee, translated, re-translated, re-organized, re-written, and re-organized again by the minds of men.
So?
That is the way science is done. Theories are modified to become increasingly accurate.
In some cases, theories can't be modified to account for new data, and are replaced by new, and more accurate, theories.
Why do you expect that a theory has to be unchangeable, and why do you criticize science when it modifies theories to be more accurate?
This is a serious question, and I would like to understand your reasoning.