Greetings mico san !! There is a cut-off date for the edit function. I cannot recall right off hand just how long it is, but after some number of days, a member can no longer edit a post.
For that reason also, it is always important to proof-read posts made, and then check them again after a day, or so. I think every member has up to two, or three days. . . but it could be a little longer.
NOW, that said, in some cases, you can ask a moderator to edit a post for you, if there is a good enough reason too. That will of course depend on what kind of editing you would like, and the weight of the need.