Definitely get back on that horse and persevere.
It's the trial and error that makes the whole process challenging and enjoyable.
And it'll never stop. There's always going to be something there for you to improve on.
Fin position is generally with the slot of the fin box lining up with the middle of the fin. If you want to loosen it up a bit move it forward a little, or for a little more straight line control move it back a fraction