Where do I need to apply for a visa when traveling to Greece from Changzhou?

This is handled in the Shanghai consular district.

By querying the information on Hualu.com, ordinary passport holders whose registered residence is in Shandong, Jiangsu, Anhui, Zhejiang, Jiangxi, Shanghai or applicants who hold residence permits in the above five provinces and one city need to Submit your visa application to the Greek Visa Application Center in the Shanghai Consular District. Changzhou belongs to Jiangsu Province, so it is processed in the Shanghai Consular District.