Welcome to the Q&A Forum

I want to update a few page titles on my website. Some are duplicate titles, and some titles are just too long. Will my website be negatively impacted at all if I update these? I read somewhere that once you have created a page you need to stick to the title you have given it. So I am not sure if I should leave these pages be and make note of utilizing better SEO practices for the future or if I can go back and edit them. Any insight is much appreciated!