Hi Barbra
Firstly you should make sure you have taken advantage of the latest available OS revision for the Geo7
The Geo 7X Operating System v6.7.18 and can be downloaded for free from here - the release notes provide further information on what the update contains, how to install it and most importantly to back up and unsaved data (on your SD or PC) before performing the update.
The Geo7 uses a combination of a single default home screen application shortcut and a smaller shortcut list.
Both options can be configured or enabled/disabled

To edit/ setup the default home-screen
Select SETTINGS > HOME > ITEMS > With Trimble Home enabled select Options

The Home Screen default application will represent the single large shortcut menu on the home screen

The application shortcut list lets you select multiple applications to sit on the home-screen below the default application.