Start by uninstalling Rebuy JS globally. Within your Rebuy Admin click on Account > Settings and switch "Enable Rebuy JS" to no, then click Save!
Now you will need to load Rebuy JS manually into your theme code on any page you have widgets in use. For example, most merchants have a widget on the Product Page, (commonly used is the product.liquid file) but this varies from theme to theme.
RebuyJS Script to Place:
<script async src="https://cdn.rebuyengine.com/onsite/js/rebuy.js?shop={{ shop.permanent_domain }}"></script>
Common Pages and their shared files:
Home Page: index.liquid
Product Page: product.liquid
Cart Page: cart.liquid/ cart-template.liquid
Remember, these vary from theme to theme, so placement may be different! You can verify Rebuy is loading on the correct page by checking the console/ network tab in your Developer Tools.
Boom! Rebuy will now load only on the pages you've told it to.