Checkout: Change fonts and colors
If you need to change your checkout fonts or link colors, you'll find them at the bottom of the Checkout settings.
Open the Theme Editor. For a draft theme, use the Customize link for that theme:
If you're using a live/published theme:
Under Theme settings (1), Checkout (2):
Scroll to the bottom and you'll find the Typography and Colors options:
Save your changes with the Theme Editor's save button on the top right.