Text Adverts - Custom Icons
Swapping these icons out is not something which is part of the theme's default functionality.
As such, this will need custom coding attention to achieve. As per Shopify's official help guides, all third-party theme developers regrettably, do not provide coding customisations:
To provide more context for this - our themes use either Font Awesome or Feather which means the standard icon-references just need to be swapped out by the custom coding Expert, with your preferred choice.
We have a page available which lists our recommended coding specialists who should be able to accommodate your needs and alter your theme's core code to suit: