I keep mine set a 700 degrees Fahrenheit. You shouldn’t have to leave the iron in place for too long to get the solder to melt. You might also want to get some flux. Using flux will help the solder flow and make the whole process easier. This is great whenever you’re working on modern electronics since manufacturers use lead-free solder these days, which is much harder to melt. I recommend using 60-40 lead-rosin solder. Good luck with your repairs/modifications!