Position on mission planner keeps on moving

hello people i am a newbie on this things and yesterday my copter went away can you people answer this doubts 1 on mission planner gps gives me 3d lock but the image of the copter in the dysplay doesnt keep in the same place ,just moves around and also when calibrating the onboard compass gives me errors and i even have reset the board but the same message bad compass health after changing to 7m gps i was able to calibrate it but gives me 15 degrees of and should the light on gps when fixed be blinking ? sorry for so many answers but i really apreciatte the help for someone o knows about this for me dont be scare of flying it best regards