Home position is where you will program Home position manually. This will not change on its own and is visible also without a GPS signal. You can reprogram it by selecting new Home position if you are using Return to Home function.
If it was not programmed yet, then it detected Home position from your Internet Provider location. For this reason you can see big difference.
Yellow dot is currently measured position which is only for your reference.
For Compass Calibration please check this page if you have not seen it yet.
https://manual.spirit-system.com/index. ... alibration