I know exactly how you feel! I got horse 8 days ago for my daughter and he presented problems as soon as i brought him home. My daughter became very upset a couple of times because of his spooking and nervousness but being an old hand and (semi)confident handler, i was able to work with the horse everyday and helped to desensitise him to his new busy, noisy surroundings. She also has an amazing instructor who helped choose the horse, and so I know the horse is a gud'un. The settling in period can be fractious and daunting to any horse and they need time to adjust.
He hardly slept the first 3 nights as his stable showed signs of him box walking and he bolting down the road on one occasion. But, with patience and experience both horse and rider are showing great signs of gaining a good respectful bond.

I showed my daughter some self belief videos and talked to her, building confidence in herself. The horse is young and, as like in a pack like situation is looking for guidance from a trustworthy, alpha source. Im trying to teach her that through respect and determination, this is the role she must provide. But I couldn't do it also without help, so consider getting some, it will be worth it in the end.

Its gone great today, but tomorrow may be a clean disaster, but everyday is a step forward and a learning experience. move forward and be determined and focused. You will get there. And Good Luck!!