When a recipe says'; cook';, does that mean on medium heat?

I'm making Dulce de Leche for the first time and I really want it to come out good. I need to cook the milk but I don't know if it needs to be on medium or hi heat! Keep in mind that this is in a heat proof bowl over water.When a recipe says'; cook';, does that mean on medium heat?
you should start out on medium heat first. If it doesn't cook fast enough turn it up a little at a time.When a recipe says'; cook';, does that mean on medium heat?
Have the heat between med and high, if it starts to boil rapidly then turn it down a little.


good luck with it
mostlikely medium
Go medium - milk souldn't be boiled. Heat it til there are some bubbles, but not furiously boiling, or you'll scold it.
Medium heat.... high heat will burn the milk..and give it a flat taste