most internet forums have this limitation of blocking editing after some time. I don't know if 10 minutes is the right amount of time, or perhaps 30 minutes? But generally if and when forums are left wide open to edit any time, it will be abused, not only by spammers, but also by dishonest posters creating drama and controversy.
Think of a forum like a place where you express your thought, just as you would in real life speaking it; and once it comes out of your mouth, it's a permanent record. In other words, maybe in the future think twice before posting and check your words before you hit the post button. so then you will have 10 minutes in case there are some typos...fine. beyond that and you are attempting to change history. You said. live with it.