Why 127.0.0.1:8080/wp jump into 127.0.0.1/wp automatically?

My wordpress was built on 80 port of apache2. Now i change apache2 configuration file,to make port 80 into 8080, everytime i input 127.0.0.1:8080/wp in the firefox ,it jump into 127.0.0.1/wp automatically, in order to visit my post,i have to input url in the form of http://127.0.0.1:8080/wp/?p=1938 ,it will not jump into http://127.0.0.1/wp/?p=1938,i wander what result in the jump from 127.0.0.1:8080/wp into 127.0.0.1/wp . it is the cache in apache or cache in firefox?If it is the cache in apache that result in the fact,how to close the cache function in apache2(in debian8)?