Changing the text on the banner

Without looking at the code, my guess would be that the text is the site name and description.

Try looking under settings / general.

As for the font color, it’s an inline style (bad practice). Best solution would be to add a class to div in question, and to move all those styles into style.css
Than you have to change ‘color’ value to whatever you want.

If you are using bought theme, you should make a child theme, so your changes are not overwritten when the theme is updated.