If you want to change something about Reach, you should do it through the child theme.
A child theme is simply a theme that inherits the functionality and looks of another theme – the parent. The whole idea of a child theme is that you can modify, and add to the functionality of that parent theme without modifying it directly.
By using a child theme you don’t need to worry about losing your modifications when you update WordPress or your theme. Only your parent theme is updated – your child theme remains intact.
Using the Child Theme
Using a child theme is no different from using any other theme. From your WordPress Dashboard, navigate to Appearance > Themes and set your child theme to Active.
Then you can work with the theme as you normally would.