Not yea, not ya, not ye - two of those are different words entirely.
If you want to transcribe the word people say when they're agreeing, or saying "yes" - it's "yeah". That is the only correct way to spell it.
This is right up there with misuse of homophones as a pet peeve for me, especially in published materials and from people who write for a living. This is something you should have cottoned to years ago. Honestly, it's not hard.
What are your spelling peeves?