1, subject 3 can be re-signed. If you forget to sign just after you leave the examination room, you can usually go back and sign again. If it takes a long time to remember after the exam, you can also explain it to the test center staff or ask the coach for help. Under normal circumstances, the staff can ask you to make up the sign.
In most cases, it doesn't matter even if you don't sign it. According to relevant students, not signing after the third exam will not affect the uploading of scores. Only when the signature is completed can it be possible to make an appointment for subject four.
In addition, if the signature is incomplete, the driver's license can't be made, so even if you forget your signature, the follow-up staff will remind you to make it up. Just in case, it's best to sign your grades after every exam.