Title/button/text Color

Hello,
I am having trouble changing the title color and button color of the first section ( I do not think it is responding to the quick edit toolbar when I change the colors or I am just missing something) as well as the Title and subtitle text in the third section. Both sections have pictures behind them that make it hard to read the default white text. I am trying to change it to #666666. If there is another way to change it or a css I can use would be amazing.
omnioptimization.com

I hope you are well today and thank you for your question.

You can try achieving this by adding the following CSS code in the Custom CSS option of your theme on the below path.

Admin Area -> Appearance -> Customize -> Additional CSS

/*header menu color*/
div.col-md-8.col-md-offset-2.col-sm-10.col-sm-offset-1.text-center h1 {
    color: #fa17fa;
}
/*button color*/
a.btn.btn-lg.btn-filled {
    background-color: #a34da3;
}

Best Regards,
Support