When I'am editing this question, can I replace the default edit summary with my own edit summary of rollback?
What way should I do?
Here's how to add an edit summary to a rollback:
- Open up the revision history on the post you wish to roll back.
- Click "edit" on the revision you wish to roll back to.
- Type your reason for rolling back into the "Edit Summary" field.
Just so that it's clear, the revision history can be found by clicking on (e.g.) "edited 2 hours ago". (For your question that should take you to this page.)
Because you don't have full editing privileges, which are unlocked at 2,000 reputation, you will only be able to do this on your own posts. If you did need to do a rollback on someone else's post, you can get the markdown of the revision you want to rollback to with the "source" link in the edit history, then edit like normal, replacing the body with what you copied.