"How do I customize buttons on my site?"
Click Edit Theme > Button Style. Here are your options for changing the style of any buttons that appear on your site. You can choose between a "flat" look or a softer, curved look.
Your button color is the “secondary” color in your applied color set.
It is important to add a hyperlink to your buttons, otherwise visitors won't be able to click them. Click the hyperlink icon in the formatting toolbar and add your link. You can choose from internal links (pages within your website) or link to an external website.
You can also apply additional formatting to your button, as with any block text.