I don't actually know how these thins work, apparently prettier explains how to make it the main formatter on their page:

{
  "editor.defaultFormatter": "esbenp.prettier-vscode",
  "[javascript]": {
    "editor.defaultFormatter": "esbenp.prettier-vscode"
  }
}

but i dont even know how to set this things. anyways, my question is, after i complete my writing, when i type ctrl s (save) on my vscode, it used to make it, well, prettier. but now it doesnt change anything (and it is not pretty at all).

now, at the bottom right of the screen, i see this:

Depending your formatter settings, when you save a file it should work as you expected.