You can gain client trust by showing strong portfolio and work samples. These day's clients do reverse search on samples so make sure your samples are yours and not copyrighted.
You can update your profile and edit your profile overview, expand it with your new skills and experiences. Take a few tests to showcase the new skills you have acquired. You may want to consider checking out these helpful blog articles to help you write winning proposals, improve your profile and tips on how to be successful on Upwork. Feel free to reach out if you need further assistance.