Pre-set #235 is a "Blank Pre-set" that you can use as a base to create new pre-sets.
There's only one "Blank Pre-set" but once you edit it, pressing the "Store" button will ask you where you want to save your changes, just store it to another slot and don't overwrite the "Blank Pre-set" and you'll be all set.
If you do overwrite the "Blank Pre-set" you can use VoiceSupport 2 to delete pre-set #235 and it'll be restored back to its factory blank state.
To change pre-sets on VoiceLive Play you need to use the on-board up/down foot-switches to scroll.
Note: The Switch-3 foot-switch cannot be used to jump to a specific pre-set.
Here's a list of what you can map to the Switch-3:
-1 Button Looper