To update the cost prices in bulk please follow the steps outlined below.
Please select inventory-> inventory & listings
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Next, please select "Cost Price" and select "Empty" - located on the left side of the page.
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The below page will then appear, In this example there are a total of 6 products without a Cost Price:
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Next, please select all listing and on the top right select : "Bulk Updates" and "Bulk Edit"
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The below page will then appear: Kindly select "Cost Price and "Next"
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Next, You will view a list of Bulk Update Product Details: from here you are able to add your Cost Prices.
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Kindly select "Save changes" and you are ready to go.
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