Hello,

01. You can change the font by means of the Advanced typography option, which allows you to choose the item from a drop-down or insert your custom CSS class. Please navigate to the Theme Settings > Typography > Advanced Typography.

Here is the documentation providing more detailed instructions: https://xtemos.com/docs/woodmart/advanced-typography-settings/

02. Please try adding the following Custom CSS in the Global Custom CSS area under Theme Settings >> Custom CSS.

body .whb-sticked .whb-general-header {
    background: orange;
}

03. Try to use the buy now button. Navigate to Theme Settings > Single Product > Buy Now > Select the redirection checkout page.

Best Regards.