Purchase the reset item, open your inventory, and select the book to return all points for reallocation. Unit Stat Rerolling
For individual units, you don't just "change" stats; you them to get higher grades (e.g., moving from a B rank to an SSS rank). Anime Story Script – Stats Changer
If you have misallocated your stat points and need to start over, you can perform a full reset: Purchase the reset item, open your inventory, and