Thank you for contacting us and I'm sorry about the issue you are experiencing. What account email address and password are you trying to change? mSecure 5 is the first and only version of mSecure to use an account system and I see no mSecure account under your email address. You'll have to create an account in order to get started with mSecure 5.
Note: this website (https://support.msecure.com) uses a separate account system meant only for support.