APM2.6 direction issue


i am beginner for APM board, earlier i was using KK2.1.5 board and i was much confident about to control drone in any direction.

just i moved APM board for other good purpose like GPS lock. stability and photography.

I configured all things by watching YouTube videos some online tutorials and some RnD.

now my issue is little bit difficult that i am not able to understand.

so When my drone face is front(Arrow on board oppose to me) and my face is same direction, my drone is working properly, like when i moved my remote stick front than drone moves front(Roll & Pitches working fine ad per configuration. when drone direction change about 90 degree than roll become pitch and yaw gets disturb. and am not able to control my drone.

any idea why this happens ?

tried many things but no success.