What are the symptoms of thyroid problems, and what works to correct them?

My manager and I have been trying to lose weight, and she was recently took a blood test to find out if everything checked out with her body. She was eating well and working out hard, but still not losing weight. She had come to find out through the bloos test that her thyroid was off. Since then she has been droping weight like its her job. I am a 5“8 male and currently weight about 185lbs. I want to lose those last 10–15lbs, but is seems that with all the workout an nurition I can not drop that weight. I have seem to became that person that walks past the bakery gains a pound.