Are you talking about changing the Movie Menu templates themselves?
The program will only create as many scenes on a menu page as it needs. In other words, if your template has room for four scenes but your movie only has two scene markers, your finished menu page will only have two scenes on it.
If you actually want to physically change template, it gets a bit more complicated. My Photoshop Elements/Premiere Elements books on Amazon take you step by step through the process of modifying and creating Movie Menu templates -- but it's not an easy process if you're not familiar Photoshop layers and layer sets.
How comfortable are you with editing layers and layer sets in Photoshop/Photoshop Elements?
But maybe we can figure out a solution once we know more specifically what you're trying to accomplish.
The DVD I have just completed carried 8 menu scene markers. The program produced 2 scene menu pages, one with 6 buttons, the second with 2 buttons. Due to the subject matter of this particular movie it would have been nice to have the option of having 4 buttons on each page.
There is, if you are willing and able to change the Movie Menu template itself using Photoshop Elements.
You can also post your request to the Community Forum of Premiere Elements support site Muvipix.com and someone there will likely be glad to create a modified or custom template for you.