You can edit alerts you've set up by clicking on the pencil icon under the "My Alerts" section. Clicking on the settings cog ...

Want to know who’s messaging you without even unlocking your phone? WhatsApp allows you to assign unique notification tones ...

Hit the blue "Update alert" box. And if you want to have all your alerts delivered at a specific time, hit the gear icon to the right of the words "My alerts" and choose a time for delivery.