GPS horizontal shift

i am using a Cuav Neo 3 GPS , and it gives me a precise location but not accurate one. i mean that after multiple test the GPS is showing a shift error from the actual location i am specifying.

this is an illustration to what i mean

any idea about the problem ? is there any parameter in mission planner responsible for that ?

No, there is no software parameter to fix that. but you can fix it by using RTK with RTCM or NTIP corrections.