If it were going to change history, it would already have done so and we wouldn't know any different, although you might. Have you read our history books?
Sending you back to the wrong decade would definitely change history and isn't something we're planning on. But we can't do it yet, anyway. Maybe it's not even possible.
I'm sorry. It doesn't make sense to me, either, but I'm trying to figure it out. I've got the scientific background to, anyway, and that helps a little.