Don't stress ..your on a wave board ..it's made for turning and looser than a longer board.
the other guys have said it all really .paadle up straight and pull the board with your feet toward the paddle as you pull it through.
that will straighten it up
It will come with time ..
when I jumped on my Hokua for the first time ..it was all over the place ...that's loose ..
basically you have to straighten it up with every paddle .

Paddling time

will sort your problem out .young .Dave .