Perhaps you should try some spelling variations:
when changed » when change, been changed, we changed
changed john » change john, changed our, changed post
wang yao » wang yan, yang yao, gang yao
yao yang » yang yang
wong siu » wong shiu, kong siu, wong sau
yang a » yang ka, yang _, yang 8
a when » 3 when, 4 when, 1 when

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: wang yao yang a when changed john ((cong shu) or (wong siu)) ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: wang yao yang a when changed john ((cong shu) OR (wong siu)) ;.
• Adding a wildcard symbol may retrieve word variants: wang yao yang a when changed john ((cong shu) or (wong siu)) ;*.