To change your password, login, open a return and then select "Account Settings" from the bottom of the black left side menu. This will open another page for the Intuit Account Manager. There select "Sign In & Security", then click on "Password" and you will be able to change your password.
When you update your password in TurboTax, it will update it for all the years that you login to using that username.
You have clicked a link to a site outside of the TurboTax Community. By clicking "Continue", you will leave the Community and be taken to that site instead.