Hammer- generally, bigger == slower but more precise. However, your setup is slowed down considerably. Slowly, only in increments of (at most) 10, increase the expo values toward zero (the larger the negative value, the less sensitive around center). Each time you change it, take it out and fly it and see what you think. It's a little slow that way, but if you move it too much at once you can get in trouble.

The percentage rates are in relation to total travel. If you get to zero expo and you want more travel on low rate, you can increase it up to 100%, but if it's set up right, then 100% will be mechanically as far as you want it to move, so unless you can verify there is more mechanical travel beyond that, I wouldn't touch them at first.