If it's anything like mine (a Goodmans), then when you have recorded one session, the "root" or index for the disc shows a title for that item and then one below it which will be for the next session, and so on. To make the disc readable on another machine, it must be finalised when you have put all you want on it. When the machine is showing you the title blocks as above, use the arrow keys to go UPWARDS. This should give a new menu to enable editing of the title or FINALISE which is what you need to do. It takes two minutes or so, so be patient.
Good luck