I had double and blurry vision for years when I relax my eyes but when I concentrate it become one clear image I am now 23 years old?

Sounds like a. Phoria is present. A phoria is a tendency for the eyes to become misaligned. You have ability to keep the eyes in alignment most of the time, but when tired, you are unable to do so. The eyes become misaligned and you get double and blurred vision. Glasses with prism in them will help alleviate this problem. See an eye doctor.
See an eye doctor. You need to see an eye doctor to see if you need prescription glasses and to see if your eyes move correctly together.