One boob over the other

Molly
My son is 5 days old and I had decided not to breastfeed due to the trouble I had with my daughter. However, I woke up yesterday with very swollen boobs and decided to try to bf. He latched on great and is doing very well. Everything my daughter was not doing. I decided to keep it up. Now I think he's decided he prefers one side to the other. How do I fix that??