In versions 8.0 and earlier of the BMC Remedy AR System Developer Studio, the form properties were accessed with the Form->Form Properties menu to open a dialog box. This has changed in AR System 8.1. I spent a lot a time wondering what I did wrong (and switching between base and overlay modes). But I finally found it. The form properties are now shown in the Definitions tab beside the view tab(s):
You should be in Base Development Mode to modify the form properties.