How does layperson know which one's most authentic in fatawa where there's difference of opinion? I sometimes choose one randomly without looking for the easiest fatwa, is this wrong? Do i need to go back& study the daleel of each I chose in this manner?

Ustadh AbdulAziz al-Haqqan

You should always look at the evidence, because any fatwa is based upon the Quran and the Sunnah. If both parties are equal to you, then you should choose the mufti whose knowledge and piety you trust the most.