That's normal. Task scheduler may want to run a job even when you are logged out and needs your credentials to log in. Your username appears on the sign in screen when the system boots up and the password if you have one is what you enter after you select the user. If you don't have a password just leave that field blank when task scheduler asks for it.
Click on the windows icon in the lower left of your screen. Your username should appear at the top of the list.