You can modify the Controls palette, which contains objects for front panels, and the Functions palette, which contains objects for block diagrams.

Adding Palette Categories
Create custom palette categories in LabVIEW to organize top-level items in the Controls or Functions palettes effectively.
Adding Palette Items to the Favorites Category
Add frequently accessed items to the Favorites category on the Functions palette for easy access and organization while building the block diagram.
Adding VIs or Objects to the Functions or Controls Palette
Add VIs or objects to the Functions or Controls palette or subpalettes to use in a new or existing VI.
Adding VIs or Objects from the Functions or Controls Palette
Add VIs, custom functions, or custom controls to the Functions or Controls palette and then add those VIs, functions, or controls to a new or existing VI.
Adding VIs and Controls to the User and Instrument Drivers Subpalettes
Add reusable LabVIEW VIs and controls to the User Controls and User Libraries palettes. Add instrument drivers to the Instrument Drivers palette.
Changing Palette Formats
Organizing Palette Categories
Showing and Hiding Palette Categories
Deleting Empty Slots on a Palette
Editing a Palette Set
Editing Icon Short Names in a Palette Set
Inserting Rows or Columns in a Palette Set
Automatically Updating Palette Sets
Sharing Palette Sets
Customizing LabVIEW Subpalettes
Customize LabVIEW palettes further by modifying subpalettes—palettes that appear within another palette.

LabVIEW User Manual