Bulgaria tutorial? Exactly what game are you playing?

M:TW 1 archers can "fire at will" when appropriate button is pressed (upper right corner). It is on by default. They will also fire if you press left mouse on an enemy unit within range (you can tell by green arrow, not red, while hovering mouse over enemy). If you press left mouse while cusor is red, they will march towards the enemy untill they are close enough to open fire.
They will run away from enemies that come too close, unless you turn off "skirmish" by selecting "hold formation".
So, sometimes, facing a fast enemy that holds quite a hight advantage can actually close the window of opportunity for your archers, as they won't get within range and notch arrows before they try to skirmish back.

Hope this helps,

/KotR