We have had problems with people removing large amounts of the opening post in a
thread; this makes the answers incomprehensible and we set a time limit after which ordinary users can't edit their posts. I can't remember what the current time limit is.
If you have something specific you wish to edit after the timeout, you can ask one of us mods.
And we usually discuss this sort of thing in the "RO" forum, so I shall move you there. I hope Rob Jelle and Roberto don't mind.