You can change the titles or headings for cross sells by going into Settings in our app:

To change Product Cross Sell headers, change the values under Product Detail Page Settings -> Section Headers

To change Cart Cross Sell headers, change the values under Cart/Basket Page Settings -> Section Headers

To change the headers for the Upsell Popup, go to Settings > Quickview & Popup Settings -> Add to Cart Pop-up -> Settings -> Title

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