I agree that you need to check the elevator direction.

Also, check to make sure you have the main gear installed correctly, and don't have the main wheels too far back, that can make it hard to rotate for takeoff. You want the mains just behind the CG. If you set the plane down on a flat surface, you should be able to push down lightly on the tail, and the nose should come up. If it takes a lot of force to raise the nosewheel off the ground, your mains aren't located correctly compared to the CG.

Set the CG as per the plans. A little nose heavy is ok, tail heavy is probibly not a good idea. But if you are too nose heavy then you have the problem with the gear being too far back.

Are you flying from grass or pavement?

On grass, you want a trike-geared plane plane to sit either level or slightly nose-high. A little nose-down is ok, but not great. If you are nose down, the nosewheel digs in, and you can't get up to speed very well, and you have to apply a lot of up elevator to get the plane to rotate. This can result in an abrupt takeoff in to a stall. On grass, being slightly nose up helps keep the nosewheel from digging in and allows you to get moving. But be careful about being too nose up, if you are too nose up, the plane can leap off the ground too soon. So, if you're on grass, you might try a larger nosewheel.

Also, if you are on grass, what size wheels are you using? Many sport planes, espeically ARFs come with wheels that are just too small for anything like a typical club grass field. (I've been to fields that looked like golf-course fairways, but most look like a close-cut house lawn, and for that kind of thing, you need larger wheels, at least 2", with 2.5+ being better)

On pavement, you usually want to be slightly nose down, but NOT nose up. If you are nose-up on pavement, it gets hard to land, you end up bouncing all over the place. And you run the risk of getting off the ground too quickly.