Kabbalah teaches that the numerical value of the word Amalek is 240 which is the same as the numerical value for the word “safek” meaning doubt. When it is written that Israelites overcame Amalek, what it really means is that they were able to overcome their own doubts.
The specific miracle that convinced Yitro to change from the negative to the positive was the victory of the Israelites over the nation of Amalek.
The message here for us is that when we overcome our own doubts and challenges, we never know what kind of positive change we can inspire in other people.
When you truly change yourself, you inspire others to also make a change.