Alteration, Change
noun, verbal noun
Things that change and renew are going through alterations and change. Pretty straightforward! Unlike 変化, which is used for spontaneous changes, 変更 is used for deliberate or planned changes, like changing an appointment, modifying rules, or altering a plan.
へんこう
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
パスワードの変更をしてください。
Please change your password.
サイズ、変更してもらったら?
What if you ask them to change the size?
予約していたディナーのコースの変更って、今からできますか?
Is changing the course for the dinner I had reserved something I can still do now?