change for the better
1. noun A change (as in, e.g., circumstance, disposition, a situation, etc.) that ultimately leads to or results in a more positive situation or outcome. He has started drinking a lot less, which is definitely a change for the better. Moving overseas was a huge undertaking, but I feel like it was a change for the better in the end.
2. verb To change in a way that ultimately leads to or results in a more positive situation or outcome. Ever since her divorce, Mary has really changed for the better. The new prime minister is changing the country's foreign policy for the better.