Hello mark_pr,
Thank you for your question about social media icons. Replacing those icons is a deceptively difficult task. The amount of HTML/PHP/CSS training required to replace those would require many pages of information and many hours of study.
The best option in your case, to avoid hiring a “guru,” would be to remove the social media area BoldGrid comes with and add a third party widget via a WordPress plugin. Some plugins provide custom buttons you can choose from, and they are very easy to install. Even if you do not use the BoldGrid buttons, the widget area remains for whatever content you find more suitable.
For something more dedicated to your unique branding style, hiring a developer would not be as dire as you might think, and you are more likely to get exactly what you need. BoldGrid is ideal for developer work because it is open-source free software that can be modified at the core level by any experienced web developer.
Best,
Christopher M.