Unity Control Center is deeply integrated into the original Ubuntu operating system with the default desktop environment Unity and that's the reason why it has to be the default Control Center. When you want to have the GNOME Control Center as default, you should consider to install Ubuntu GNOME with the default desktop environment GNOME, it's up to you to decide what is more important for you, using original Ubuntu or using integrated Office 365 account.
Please note that this answers the main question about making GNOME Control Center being default, I can't guarantee that Microsoft Office 365 service integration works properly at all - because when it comes to "Microsoft loves Linux" ... well, I don't wanna say too much here ...