How to change the build configuration ?

hi,
I am using Qt 4.7.4. In the Symbian Device -> Build – > “Edit build configuration” it is selected “Qt 4.7.4 for Symbian Anna release” as i wanted to create sis file.
1) Can i change it to Symbian^3 release ? Actually what does it mean by this configuration selection ?
2) When i go in Symbian Device -> Run mode and plug a device E7-00 it doesn’t show the Device name and Serial port is blank. What should i do?