You can simply customize the text of your button on the “Widgets” page.
Follow these steps to customize your button style and text:
On your Notify me! panel Select Widgets.
You can customize the content, Style, and Placement of the button here.
In the Style section, you can customize the Background color, Text Color, Border Color, Border radius, and Border size of your button
You can use your CSS skills to do more advanced customizations from the Advanced section. learn more about it here.