Greetings,
These settings are generally made, and they are rendered on page load. This error is only on your side, because there is some styling added by the theme used on your website.
Please try to add the settings you desire, into our CSS editor, which looks like this: https://s.w.org/plugins/contact-form-7-style/screenshot-6.jpg?r=1595508
Try adding your color, like this:
body .cf7-style.cf7-style-649 input[type="submit"] {
background-color: #e2e068 !important;
}
Important Note: The snippet above only works if you have the current custom style activated.
As for your second question, we will test it on a multi-site setup and add a fix for it in our next release.
If you enjoy our work, please feel free to give us a five star rating or consider donating.
Best Regards,
Lehel