My father previously told me that our minhag was to light a yartzeit candle on the day of the yartzeit and yom kippur but not for the yizkors of Pesach Shavuos and Shemini Atzeres. He recently changed his minhag because someone told him that he was wrong. Understood that the candle is just a minhag and not a halacha, but is this minhag correct or should we change it?
I don’t know the source of the minhag specifically not to light a candle for Yizkor. It would be a good idea if you could research this and see if indeed there is such a minhag. The generally accepted minag however is to light such a candle. If it isn’t a real family minhag, then you don’t have any problem changing it.