It is super simple, by using our built-in customizer tool of course!
Starting at your Dashboard: When creating your plug in Step 4 (Plug Style) you will be defaulted to open the button customizer tool in order to proceed (Save & Continue) to the final step of generating your plug's embed code.
Once the customizer pop-over has opened you have the option to Save & Continue and save using the default design, or use the basic customizer to change the text and color of your button as you wish.
Alternatively, if you are feeling extra creative you can hit the advanced customizer link and customize your button's border, size and label even.
Widgets work the same way too :)