This article explains how to replace the native search bar in the Bigcart theme by C-Themes.
FiboSearch plugin features built-in integration with this theme. It means you can replace the default search bars by selecting a single checkbox.
If you have activated the Bigcart theme or the child theme of Bigcart, you should see the following screen in the plugin settings:
WooCommerce
→ FiboSearch
→ Starting (tab)
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Select the option Replace them
and the search bar should be replaced.