Earlier quoted context omitted.
When I first bought mine I tried to adjust the temperature in what felt like the natural way to do so, without rtfm first of course. Then I quickly learned that I had adjusted the temperature calibration. I reverted what I had done but now I am not confident about the temperature its operating at, at all. Seems a terrible interface design.
Yep I did that too. I recalibrated by using the thermocouple on my multimeter. That's not my biggest problem though - my biggest problem has just been keeping tips tinned properly. I've succeeded once, but it constantly feels like a struggle.
Also keeping the tip at moderate temperature range helps avoid oxidation - most manufacturers recommend to never exceed 400 C. JBC recommends to not exceed 370 C.
Hope this helps.