Updating the values in a list?

Im trying to update the values in a list, however when i leave the function that updates them they haven't changed. Also i have to use a list i know that a vector might be much easier.

void kitchen::removeIngredient(std::string aName, int someUnits){
std::list<std::string> newList;
std::list<std::list<std::string> >::iterator replacer;
for(std::list<std::list<std::string> >::iterator iterate = ingredients.begin(); iterate!=ingredients.end(); iterate++){
    for(std::list<std::string>::iterator ritr=iterate->begin(); ritr!=iterate->end(); ritr++){
        if(*ritr==aName){
            ritr++;
            std::string newStr;
            newStr=std::to_string((std::stoi(*ritr)-someUnits));
            std::cout<<*ritr<<std::endl;
            *ritr=std::to_string((std::stoi(*ritr)-someUnits));
            std::cout<<*ritr<<std::endl;
        }
    }
}

}

any help at all is appreciated.