As you can see my stem is very blocky and not smooth. As the tutorial was making it, there was a smooth version of it under the transparent blocky part in Edit Mode. I've tried smoothing it again and even applied the scale but it didn't work.
Here is the tutorial I used.
It's probably a very easy answer but I would really appreciate some help :)
P.S. Sorry that I don't know all the language to refer to things by.