how can I change the button's order of the status bar in vscode?

There is not any official way of doing it. There is a dirty hack you can try, But it may have unexpected outcome.

Yes, You can do that by editing CSS layout file.

1. Goto .../Microsoft VS Code\resources\app\out\vs\workbench\electron-browser directory.
2. Open workbench.main.css file. Take backup just in case anything goes wrong.
3. Set .monaco-workbench>.part.statusbar to use flex using display:flex
4. Suppose you want first item to go to 3rd, create CSS class like .monaco-workbench>.part.statusbar:nth-child(1){order: 3}
5. Save file and reload VS code