Hello @adelille,
Thanks for reaching out. If you don't see the option to change your login credentials, you've logged into iFixit using another service (ex. Facebook, Google, Yahoo!).
If you used Google to log in, and you’d like to separate your Google and iFixit accounts, you can follow the steps in the [https://help.ifixit.com/article/39-edit-account-info|blue box on this page]. If you would like to separate your Facebook or Yahoo! accounts from your iFixit account, you’ll need to contact [https://help.ifixit.com/article/136-email-support|iFixit customer support].
I hope this helps!
