To be honest, I don't know for sure. Sometimes it might be feasible, but it often depends on the rights and regulations associated with that particular manhwa. You might want to look into the terms and conditions provided when you got it.
It could mean being afraid of the past events, experiences, or histories (back stories) related to a person, place, or thing. For example, someone might be scared to learn about the back story of an old, haunted house as it could involve disturbing events like murders or tragedies.
Well, usually it's possible, but it might involve certain conditions. For example, if it's a subscription-based service and you haven't violated any terms, you might be able to. But if it's a one-time purchase or has specific usage rules, it could be more complicated.
One way is to face it gradually. Start by learning small bits of the back story at a time. For example, if it's about a person, first ask about their recent past and then slowly move further back.
Taking back Manhwa Chapter 65 is unlikely to be possible. Usually, once a chapter is made available, it's there for viewing and can't be reversed. But you could explore if there are any special circumstances or options mentioned by the publisher or platform.