[Mysql 2019-09-29] long_query_time setting does not take effect?

Today encounter a phenomenon, after setting long_query_time inquiry does not take effect, as shown:

 

 Obviously the setting is successful, why or check out the original value of it?

Because the 'show VARIABLES like "% long_query_time%"' is found in the parameter acquired from the current session, as long as the re-open a session, or "set GLOBAL long_query_time = 3;" it