HI!! When I created my account I liked the username I have, but now, I don't like it and I want to change it without making another account, I don't want to restart in another account leaving behind the projects I made and the followers I won

This is in the list of rejected suggestions. See the top sticky.

Unfortunately, the ability to change usernames is a suggestion the Scratch Team has seen before, thought about, and decided not to implement to Scratch. Here's why:

The Official List of Rejected Suggestions wrote:

8.1 Changing usernames
If a user could change their username (or even set a certain “nickname”), this could be very confusing for the Scratch community, especially for those following that user. In addition, this would make moderation of the website more difficult because it would be harder for the Scratch Team to keep an eye on what a user may be doing. The Scratch Team has allowed username changes only on very rare occasions, such as if the username contained inappropriate content or personal information. Generally the Scratch Team does not change usernames on request (such as for reasons like “I do not like my current username anymore”).

However, because of the way that usernames are stored on the server, changing the cases of letters in your username (for example, changing @Za-Chary to @ZA-CHARY) is NOT rejected; you can discuss it on this topic.

Sorry to disappoint.
Thank you for sharing your ideas, though — keep thinking of new ways to make Scratch a better place.