Set/put the world to rights
Definition 1 of 2
Pro Tip 1/3Casual Conversation
Often used in friendly, informal debates or chats, not in serious discussions. 
Over coffee, we enjoyed trying to set the world to rights.
Pro Tip 2/3Figurative Speech
It's about sharing ideas, not actually solving global problems. 
Talking late into the night, we tried to set the world to rights.
Pro Tip 3/3Slight Irony
Might imply the discussion is ambitious or overly optimistic. 
They laughingly claimed they'd set the world to rights by sunrise.