WARNING: It's not advised to never edit a sales transaction unless there is a specific reason to, usually you can edit everything in the manage tickets area instead.
If you find a reason where you need to edit a sales transaction then;
1. Use the admin menu to navigate to Reports > Sales Transactions
2. Find the Sales Transaction you are looking to edit and click its corresponding link.
3. The edit Sales Transaction page will load, edit the details required and click the save button.