Archimesh, properties? In relation blender 2.79 and the archimesh tool shelf missing, which was answered in Archimesh is not displayed in the Tool shelf

The properties panel is disabled. For example when i add a column i cannot change top or base or add an arch. What do i need to do to enable it?

I posted a follow up there, apologies for that.
Go to User preferences -> Editing-> (check mark on) undo

Do not forget to save user setting below