Refer to figure.
OUTBOARD AND INBOARD AILERONS
Two sets of ailerons may be fitted, one at the wing tips (outboard ailerons) and one set inboard (inboard ailerons).

At low speeds, both the inboard and the outboard ailerons are controllable but once the aircraft gains speed (usually when the flaps are all the way up) only the inboard ailerons respond to control input. At high speeds, when the forces are greater and could cause greater structural distortion, outboard (low-speed) ailerons are "locked-out".

Due to wing elasticity, the effectiveness of outboard ailerons reduces or even aileron reversal can occur at higher speeds.