Always save your project as a project file (*.bmc) using the menu "Project - Save As ..." if you want to make changes or continue editing your project later. Then you can open the project at any time for changes using the menu "Project - Recent ..." or "Project - Open ...". If there is no project file, it is impossible to change anything in the video (move, delete, correct the text). It is only possible to add new elements or cut out unnecessary parts of the video.