I only use my trims during the first few flights. I set the trims for straight and level then when I get it back on the ground I adjust the clevises so that my trims are in the neutral position. Once the plane is trimmed properly with the clevises, I do not have to worry about adjusting the trims. I just check to see that the trims are set in the neutral position.

No, they are not easily knocked out of position. The are located near enough to the sticks to be convenient but in a way that they are not touched while I am flying. In the years that I have been flying, the only trim that gets moved is the throttle trim and that is deliberate. None have ever been moved by accident during a flight.