Perhaps you should try some spelling variations:
changed role » changed rome, changing role, changed world
changed file » change five, change fire, changed face
cogan john » hogan john, morgan john, dugan john
long tail » long haul
john wong » john song, john bonn
wong sein » ong sean, wong shiu, wong siu
long tip » long trip, long time, long did

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((long tip) or (long tail)) than ((changed role) OR (changed file)) cogan john wong sein ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((long tip) OR (long tail)) than ((changed role) OR (changed file)) cogan john wong sein ;.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((long tip) or (long tail)) than ((changed role) OR (changed file)) cogan john wong sein ;".
• Adding a wildcard symbol may retrieve word variants: ((long tip) or (long tail)) than ((changed role) OR (changed file)) cogan john wong sein ;*.