A Project Manager has the ability to change the time zone at the project level.
With a project selected and in context, go to Settings (gear icon) > Preferences.
From the Project Preferences, you not only have the ability to configure your Time Zone, but you can also customize your email notification settings.
Changes are applied immediately - there is no confirmation.
Under the Time Zone dropdown, there are 200 cities from around the world to choose from. Attached is a PDF list of all North American cities.