I am not familiar with the new version, How to re-edit and update the published posts?
There is an icon with a pen just under the post, unless you are not a trusted user yet (all users are untrusted after the migration), post more and you’ll be able to edit posts.
The post just published can be edited, but the post before migration cannot be edited
Still untrusted then.
Hello @Noda , welcome, your account now has permission to edit old posts.