Yes, you can! Just go to Settings and select Sign in and security. You can then link your Google or Apple (or both!) accounts to your Gizmo account. When you have done this, you can sign in with any of these options and not just the method you created your account with.
On this page, you can also change your email address or password. If you need to change your phone number, please get in contact with the Support team using the button below. They will help get this changed!