im aware this is a small question, but I cannot actually find much answers on it.
I would just like to confirm that even if i want to change just one line of code, I have to make a new archive, upload a new build, make a new submission in Itunes Connect, wait for review, then finally its live?
Or is there a quicker way to make small changes to apps?
No matter how large or small the changes are that you make to your app, you must go through the same complete set of steps to have your update pushed to the App Store.
Apple has no way to know the scope of your changes so the app must be reviewed again each time.
Your best option is to avoid such trivial changes. Fix a bunch of issues in each release or add new features. The best thing of course is to thoroughly test your app before submitting it to Apple. A few extra hours of your own testing will save you days of waiting and it will make your customers happier and it avoids wasting the efforts of the Apple review team.