Theme editor
The easiest way to add the widget without editing code is through the theme editor.Open the theme editor
In your Shopify admin, go to Online Store → Themes. Click Customize on your active theme.
Add a Custom Liquid block
In the left panel, click Add section (or select an existing section). Choose Custom Liquid from the list.
theme.liquid (all pages)
To load the widget across your entire store, edit your theme’stheme.liquid file directly.
Open the code editor
In your Shopify admin, go to Online Store → Themes. Click the three-dot menu next to your active theme and select Edit code.
Add the script
Find the closing
</body> tag and paste the script directly before it.layout/theme.liquid