If you start having trouble finding stories – or wondering whether the story is already in there somewhere – your backlog is probably too long 😅
The idea of a product backlog is that of a short-term buffer. A backlog lasting about 6 weeks is good; a backlog lasting 6 months is not.
The whole idea of stories is that you can talk about them when they enter the backlog AND you still know what you talked about when you implement them!
Don‘t fall for the trap of writing detailed stories so you can better remember in 6 months. That‘s not agile.
Just keep your backlogs short and nimble.
If you have broad ideas about the future, write a few keywords as an epic. But please don‘t detail user stories more than a few weeks into the future. Unless you want to do waterfall with agile terms.
Keep backlogs short.