Neve Buttons
For more details check out the full Neve documentation and Neve PRO documentation.
Navigate to Appearance > Customize > Global > Buttons to access the options (The options from the General panel apply to all other buttons, that are not primary or secondary).
Neve has two types of buttons, based on their "importance" on the page, called Primary (which have the .button-primary CSS class) and Secondary (which have the .button-secondary CSS class).
Examples of Primary buttons: Add to Cart, Post Comment, Proceed to Checkout
Examples of Secondary buttons: View Cart, Apply Coupon