Except that for some favors, it's not true that "It was not problem", even if it is true that "you're welcome to ask again". In these cases, I use "you're welco

Except that for some favors, it's not true that "It was not problem", even if it is true that "you're welcome to ask again". In these cases, I use "you're welcome". In the others, I use "no problem".