I think the central way in which this masterful story of Chinese immigrants starting new lives in the US explores the theme of change is through the differences between the two generations of immigrants and how the daughters of the Chinese women who left their country are forced to construct their own identity as they grow up as second-generation immigrants who are born in the US but nonetheless grow up in a Chinese subculture. This of course creates conflict in all of these relationships, as the mothers expect their daughters to grow up and show similar respect and obedience as they had to when they grew up in China. However, at the same time, the Chinese mothers want their daughters to learn something from American strength and independence, and integrate these qualities into their identity. The novel is really the exploration of the daughters and their attempts to find a compromise between the two extremes of a Chinese identity and an American identity that prove acceptable to both themselves and to their mothers. An excellent example would be the way in which Rose Hsu Jordan manages to assert herself in the face of her husband's cruelty after hearing the story of her grandmother.
Identity is something that is presented as being malleable and in a process of flux or change. The daughters range between adopting a Chinese approach to life and rejecting their Chinese heritage to embrace American norms and values. All of them show the theme of change by incorporating elements of both identities to create a new hybrid identity that allows them to pick and choose, showing the way in which identity is something that is in a constant process of change for many immigrants or second-generation immigrants.