My rescue cat that we took home at 4 months, sometimes get vicious when he does not want something done to him…some of those things are too much affection, nail cutting, adjusting his collar, picking him up sometimes. Other times he has been getting better behaved since he turned a year, but he’s still making me bleed several times a week. We got him to replace an emotional support cat who passed away, but he’s just not fitting into the role.
I am sorry to hear about your problems. Cats have many different personalities, just like people. Some are more anxious than others, some more affectionate, and some a bit more aggressive. It is important to make sure that you spend some time with your cat and understand its personality and learn its unique personality. There are different things you can try, and perhaps some different training tips to try. I recommend starting here on training tips 101.