You have to learn this sometime. Ben Franklin got the charge on an electron wrong and thus most times the direction doesn't matter, but sometimes it does.
"Conventional Current" goes from positive to negative. Conventional current determines the sign of the potential difference.
Electrons, however, go the other way. it matters in electrochemistry. In solid state physics is matters too, we introduce another concept: holes go in the direction of conventional current.
We pick the "conventional current" method and when we really need to know which way the electrons are going, it's the opposite of conventional current.
I hope I answered your question. I always forget which way to mark the battery polarity.