優しい and 易しい: kindness and ease with やさしい
Distinguish two spellings of やさしい through a person's manner and a task's difficulty, including explanations that are both gentle and easy.
How someone treats people
先生は質問した学生に優しく答えました。 says that the teacher answered the student's question kindly. 優しい describes a kind or gentle manner.
妹は動物に優しいです。 says that the younger sister is kind to animals. に marks those receiving the kindness, not something easy to deal with.
The difficulty of a task or content
この問題は易しいです。 means that this problem is easy. 易しい evaluates low difficulty in solving or understanding and shares the reading of 優しい.
易しい日本語で説明してください。 asks for an explanation in easy Japanese. The focus is accessible vocabulary and expressions rather than merely a gentle tone.
Two judgments about one explanation
先生は優しく話しましたが、内容は易しくありませんでした。 says that the teacher spoke kindly but the content was not easy. Manner and difficulty can receive different judgments.
Both are i-adjectives and modify actions as 優しく and 易しく. Because their sounds match, choose the spelling according to the intended meaning.
Does 易しい問題 mean a problem with a kind personality?
Show the answer and why
No. It means a problem with low difficulty. 優しい expresses kindness, while 易しい expresses ease.