Edit bug

Go to the "Home" page and choose a project.

You will see the list of all the bugs for the selected project. Click on any bug that you want to edit.

It will open the bug details page. Edit the bug as per your requirements. From this page you can edit assignee, status, severity, classification, category, state, due date etc.

Additionally, you can also add comments & attachments. You can also see the bug editing history in the "Activity stream" tab.