What do you mean by "submenus"?
Meantime, what operating system are you running? How fast is your processor and how much RAM do you have? How much free, clean, defragmented space is on your hard drive?
If you are on a Windows computer, have you manually gone to Windows Update and ensured you have even the non-critical updates, which can add important drivers and other updates to your system?
As a novice and new to this forum, I have noticed that the menus items in PRE don't become active until I open or create a project.
Perhaps the OP hasn't opened a project.
Did you launched the Welcome Screen first, or directly launched the application.
Which version of PrE are you using?
If you launched the Welcome Screen first, click on New Project or Open Project button. Applcation will launch with the new project dialog box or with a project loaded.
If you launched the application directly, create a new project using File-> New or open a previous project using File->Opne Project.
Reply with exact steps, if you problem does not get solved