No. This "has" has nothing to do with possession. Your attitude "has changed" is not the same as the fact that your neighbor "has a car" (Tu vecino tiene un coche), It is the same as "your neighbor has bought a car" (Tu vecino ha comprado un coche). "Changed" is clearly a part participle so it it has to be cambiado. "Has changed" is auxiliary verb (haber) + past participle, a very common construction in English and Spanish and it is most definitely, ha cambiado.