AppyBuilder GOLD now allows you to change application package name, even for apps with multiple screens.
WHEN changing package names AND IF you have multiple screens,you need to fully qualify screen names as shown below:
Let's assume your email is email@example.com and your app name is textingapp. Also, let's assume, you change ApplicationPackage to appinventor.aijdoe_01.textingapp
To "Open another screen" Screen2 => "Open another screen"jdoe_01.textingapp.Screen2 - IF your email includes a dot, replace it with underscore; e.g. jdoe.01 -> jdoe_01
Notice that you'll need to change the dot (.) with underscore ( _ ) in the email