Hi, Spies12345!
You can do what you've asked about by setting chapter markers. Drop your MP4 clip onto the timeline, then click on the "chapter" room(identified by a film strip with 1,2,3 on it). Chapter 1 will always be at the very beginning of the clip(fixed, unalterable), as you view through your clip, you add new chapters by clicking on the C+ icon at the point you want(where the song begins) and continue to add at each successive point(where the next songs begin, in their turn). After adding your chapters, you go to Create Disc and choose your wanted menu style by clicking on "Menu Preferences" On PD14, which I'm basing these tips there is a missing element on some of the menu templates, and that is the provision to select how many "thumbnails" appear on the menu(that's obviously one for the "Suggestions For PD15" forum). As you cannot in PD14 choose how many thumbnails in a menu, as you're using PD13, look to see if you have the option in that version. I do have it in PD8 which is also on my computer. The only thing I can suggest is have an even number of chapters that can be divided by 2, 3 or 4(2, 4, 6, 8, 10 or 12). Hope this is of help.
Cheers!
Neil.