Board Thread:Support Requests - Getting Technical/@comment-43841217-20200627030807/@comment-39340968-20200627031505

So, these are entirely separate problems

1) The password

The password can be changed by using Special:ChangePassword. The password could possibly not be the right length for signing in

2) Changing your username

Once you fix that issue, use Special:UserRenameTool.

If you continue to have issues with your password, you can submit a for that issue.