It helps to put a small amount of solder on the tip of the iron before you touch the pad - it improves the heat transfer. The main amount is added into the part

It helps to put a small amount of solder on the tip of the iron before you touch the pad - it improves the heat transfer. The main amount is added into the part/pad interface, as you saw on YouTube. I’m thinking that, when you first learned to solder, you remembered the first step but not the second one, and thus got off on the wrong foot.