You can open a pull request. If you own the pull request you can also modify it.
Desktop client
Topic stream: on the My Current Stream panel, click Pull Request.
Regular stream: on the My Current Stream panel, click Reviews. Double click the pull request.
Web client
Open a topic steam. On the My Current Stream tab, on the side panel click Pull Request.
The pull request is displayed in the main window.
On the Conversation tab you can modify these fields:
Description
Author (the owner of the pull request)
Reviewers
Request
Any changes that you make are saved automatically.
To edit the pull request’s title, from the Actions menu select Edit Title. You can also open the pull request in Pulse.