I advise against using button 0. WLED's buttons have some default behaviors written in, and one of button 0's default behaviors is that when it's pressed for more than a few seconds, it resets your microcontroller to factory settings. I originally had button 0 selected, and I held the button down a bit too long while I was sewing it onto the hat, and .. POOF. All my settings and presets were wiped out. 

Check out the "Backup" section under the Additonal Settings page to learn to back up your configuration and presets, in case this kind of thing happens to you.

In WLED, the default actions for button 1 are designed to provide basic control without custom programming.

Button 1 Behaviors:

• Short Press: Cycles to the next effect.
• Long Press: Ramps brightness up/down.
• Double Press: Cycles through color palettes.
• Default State: If no custom macro is defined, the button defaults to these built-in functions, as outlined in the WLED documentation. 

If you're happy with this, you're done! But if you want to take control of your button to do custom actions of your choosing, read on.

Troubleshooting

If your button isn't working, here are some things to try:

1. Double check both the LED preferences page and the Time & Macros page to be sure your settings are correct, and have saved.
2. Be sure your presets are correctly numbered. WLED gets confused if the presets have non-sequential IDs (so make sure they're numbered 1, 2, 3 rather than 2, 5, 7).
3. Be sure you're soldered to pin 18 on the Sparkle Motion -- the screw terminal pins will not read button presses.