The cryptic link you got from @Dr_Andy_Vishnu is to a fitness app called “myrunningapp”.
For more information, check this official thread.
Regarding your problem with GPS. I would suggest you update the A-GPS database, you can use an app like " GPS test" or GPS toolbox (I think it is the name) both are downloadable from the play store on your watch. Another thing, always allow time for your watch to get a fix before starting a workout.
If you have wifi on, before leaving the house, make sure you start the gps tracker so you get a rough position. MyRunningApp has a count down from 15 secs as default, but you can add a minute extra.
In regards to the heart rate, I use a “smart bluetooth” belt… bought it for 8 euros or so new. It lasts months on a single battery and it measures instantly and way more reliable than the built-in one. To keep BT pulsebelt connection stable, I use BT true wireless earphones with something playing.
I use kospet prime btw.