When you asked "In qa-theme ?", I think something is not right. You have to edit the main content of your plugin.
Typically, a plugin is a folder with two files. One of them (qa-plugin.php) is to register that plugin to Q2A system. The other one is the main value of your plugin. You need to edit that file and check out which functions may output the final results.
Sometimes a plugin is merely to override the layout, sometimes a plugin is to output a widget.