Editing your profile
Click your name or avatar and go to Profile to update your own name and phone number — it only ever edits your own account, not anyone else's.
Changing your password
On the Profile page, use Change Password. You'll need to enter your current password before setting a new one — this is required even for administrators changing their own password, as a safeguard against someone else using an unattended session.
If you're locked out and can't sign in at all to reach this page, use Resetting a forgotten password instead.
Next, see Troubleshooting if something isn't working as expected.