Sony CLIE PEG-S300/E - Manual (Page 228)

228
Setting Up
Y
our CLIE Handheld
To launch the original applications
When you have assigned another application to the button, you can launch
the original application with the application launcher.
To reset to the default settings
When you want to initialize the allocation for the application button, tap
“Default” in step 2. All application buttons are reset to the factory (default)
settings.