What change?
There were two groups from long before Constantine:
One group celebrated Easter on the Sunday immediately after the post equinox full moon (unless the moon landed on that date).
The other group on the same date as the Jewish Passover...the date of that full moon.
And then there's calendrical differences that last to this day (Julian vs Gregorian).
Whatever the system, to this day Easter is a moveable feast. The solar date varies based on the position of the post equinox moon.