I have read that you should draw one enemey at the time, seen youtube videos on how to do this. But in icewind dale gog edition when I try to draw a enemy all enemys nearby attacks me, make it impossible to kill monsters. Why is this happening? Any solution please =)

It only works on undead (or maybe some others). The only places I can think of at the moment where it's a valid tactic is in the tombs in the Vale of Shadows and a certain other tomb later. Sentient enemies will call for help.

In general, it is always best to gang-up on one enemy at a time with your whole party rather than engage more than opponent at once. This is because even enemies with only a few hit points left can still hit you and deal full damage, and the enemies often outnumber you even if you have a full six characters in your party. If you are trying to say reach the edge of the sight of an enemy at the edge of a group of enemies, and make that one enemy who sees you alone follow you away from his fellows, in my experience this sometimes works but not always. The best approach is simply to have a rogue or someone with invisibility sneak up until only the enemy you want to lure away is visible. Put him at the very edge of your sight, with some shadow left on him for the best results, and use a missle weapon or a spell that will reach him.

If you're trying to "pull" one monster at a time, you have to move a character so that the chosen monster is JUST at the edge of the fog of war, but you also have to NOT attack them with ranged weapons or spells. If you've gotten just barely close enough, then the one monster you can see will move towards you, and you can attack him once he gets close. If you attack him too early, he'll alert his friends... but if he's far enough away, they'll be outside of his "shout" radius and won't join the fight.

It only works on melee monsters, though, and it is also dependent on the individual creature. Some monsters will "shout" as soon as they see you, and others will shout when they're attacked. This only works on the latter type.

In the first version of IWD the monsters didn't care about the others being attacked.
But with the HoW expansion the monster AI was improved, now often the whole group attacks back when one of them is attacked. You have to find another strategy.

One strategy is to send summons ahead and have your party member shoot the monsters while they are busy attacking your summons.
Another option is immobilizing the monsters with webs and entangle and bombarding them from the distance.
If you use spells to prebuff your party the combat efficiency will improve a lot.

Thank you so much guys for helping me out. A lot of good solutions =)