Last things first: I can move a thread to another forum. Because I'm a moderator I don't always know what can be done by those who are not moderators, but it's generally easy enough to ask me if I can do something.
I can also edit posts forever, and I can close and "unclose" threads. I don't think that's within the power of ordinary users. I do know that users (other than moderators and administrators) have a limited edit window--I believe we set it to one week. This is supposed to prevent people from going back and editing their previous posts after others have responded to them while still allowing them a couple days to realize there are errors that need to be addressed. If it was more than a week between when you posted and when you tried to edit, that might be what the system was telling you.
I can look at it and try to fix it, but I don't see the thread and you didn't include either the link or the title.
--M. J. Young