Everybody that speaks, writes, sings, etc to you directly or as part of a group would be physically incapable of saying something they knew to be untrue. Anybody attempting to lie would uncontrollably tell the truth instead. This only applies if you are physically in the audience. Example, btoadcasts and pre-recordings would not be covered by this, but all live performances would.
Or
You have a device, about the size of a mobile phone, that allows you to see and hear any event that has occurred. You only need to provide coordinates and a date to observe what happened at that place and time. Only events that are occurred 10 years or more ago and occurred on the planet Earth (up to 5 mi / 8 km above the surface) are accessible. You can swivel your perspective, but you cannot move around (so no following if your subject leaves the area or moving to peak behind / under anything). Once you start viewing a moment, events play out in real time and you can watch as long as you want. Nobody but you is able to witness the events and you cannot make any recordings.
If the lying thing was universal, I’d go with that. The world would be better if the powerful couldn’t lie.
But just lies to me personally? That’d barely change my life at all.
Seeing anything in history though? That’d be amazing. It’d be work, but I could probably witness events and then work backwards and publish papers on it using publicly available information. Knowing the answer to start with would certainly make that sort of thing easier.
You could attend any public, political event (speach, townhall, congressional hearing, etc), court proceeding, religious ceremony, fund raising event, press conference, etc and nobody within earshot of you could say anything they knew to be untrue.
Might also make going to bars and clubs more interesting.