This can be improved with skin lightening and certain lasers/peels but often is permanent. Please see a cosmetic dermatologist with experience. Best, Dr. Emer.
Thank you for your question and I am sorry to hear of your scarring issues. The first step would be to moisturize your legs and arms well and use a sunblock to prevent pigmentation changes from the suns UV radiation. A lightening cream such as hydroquinone can then be used to lighten the scars' appearance but If after a few months you see little change, chemical peels can be performed. I am attaching a link below with additional useful information.